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Subject: Earth Science

Teacher: Mrs. Yiatrou

Curriculum Topic: Minerals & Rocks

Learners: High School- 10th

& 11th

grades, Level 3 and 4 learners

- Students work in groups of 4

Curriculum Links: Students have been introduced to Earth’s Systems, the Scientific

Method, Communication of Scientific Data & Results, Mapping, Matter & States of Matter

National Standards:

C.4.a. Core Competencies. All teachers of the Earth and space sciences should be prepared

lead students to understand the unifying concepts required of all teachers of science, and

should in addition be prepared to lead students to understand:

1. Characteristics of land, atmosphere, and ocean systems on Earth.

2. Properties, measurement, and classification of Earth materials.

C.4.b. Advanced Competencies. In addition to the core competencies, teachers of the Earth

and space sciences as a primary field should be prepared to effectively lead students to

understand:

19. Issues related to changes in Earth systems such as global climate change, mine

subsidence, and channeling of waterways.

Scope & Sequence: (15 days)

Minerals

Igneous rocks (intro with rock cycle followed by volcanoes)

Metamorphic rocks

Sedimentary rocks (intro – taught with weathering)

Mining & natural resources

- In this section of the curriculum, students learn about the processes that form and shape

the rocks that make up our landscapes. They begin with some fundamental chemistry to

learn what a mineral is. They then build upon this understanding to distinguish between the

different types of rocks and minerals that exist. Understanding how these different rocks

form and change requires learning about the rock cycle which explains what happens to

rocks both above and below the Earth's surface.

Lesson 1:

Goal: Students will be able to identify differences between matter & elements and compare

physical properties of matter to its chemical properties

- Mineral characteristics

- Naturally occurring & inorganic

- Definite crystalline structure

- Solids with specific composition

Motivation: Show the class a sample of halite and have them describe properties of the

crystal.

NYS Standards:

3.1a Minerals have physical properties determined by their chemical composition and crystal

structure.

- Minerals can be identified by well-defined physical and chemical properties, such as cleavage,

fracture, color, density, hardness, streak, luster, crystal shape, and reaction with acid.

- Chemical composition and physical properties determine how minerals are used by humans.

3.1b Minerals are formed inorganically by the process of crystallization as a result of specific

environmental conditions. These include:

- cooling and solidification of magma

- precipitation from water caused by such processes as evaporation, chemical reactions, and

temperature changes

- rearrangement of atoms in existing minerals subjected to conditions of high temperature and

pressure.

Mini-Lesson (10-15 minutes):

Connection: New topic: Geology and geological processes of Earth

Teach: Matter- physical & chemical properties, elements

Model / Demonstrate: Illustrations, overhead, handout

Student Engagement: Discussion

Workshop (20-30 minutes):

Identifying elements:

Using Periodic Table of Elements; identify element symbol, atomic number, and atomic

mass of hydrogen, helium, oxygen, carbon, gold silver, iron, sulfur, sodium, potassium,

magnesium, nitrogen, calcium

Shareout

Journal: What is matter?

Homework: Read text p. 30-36; make notes

Handout

Lesson 2:

Goal: Students will be able to define what an atom is, identify its structures and their properties.

Motivation: Demo- Charge a glass rod w/ static electricity by rubbing w/ silk cloth. Cloth

removes electrons. Produce electrical sparks by holding rod close to a metallic object. Have

students explain (sparks consist of electrons attracted by positively charged rod)

NYS Standards:


structure.








temperature changes


pressure.


Connection: Geology and geological processes of Earth, matter- physical & chemical properties,

elements, atoms- # & mass, isotopes

Teach: Definition, structure, protons, neutrons, electrons, atomic # , atomic mass, isotopes




Create a diagram / model of an atom with given material and label

Shareout

Journal: Cu has 29 electrons. Draw a diagram of an atom of Cu that shows the placement of

its electrons in correct energy levels and the number of protons it has.

Homework: Read text p. 34-36; answer ques. 3, 4, & 5 on looseleaf

Diagnostic Properties of Minerals

There are eight major diagnostic properties of minerals: crystal habit, luster, hardness, cleavage,

fracture, color, streak, and specific gravity. Generally, there is no single diagnostic property which, by

itself, can be used to identify a mineral sample. Rather, we must rely on a number of diagnostic properties

to reach this goal.

Crystal Habit

If a mineral crystallizes without any impediments to its growth, it may assume a characteristic shape, or

crystal habit which reflects its internal crystal structure. Some common crystal habits are illustrated in

Figure 1-6. The term anhedral is used to describe minerals without well-formed crystal habits (which are

vastly more common in rocks).

Luster

Luster refers to the way in which light is reflected from the surface of a mineral. The two basic classes are

metallic luster, which describes the reflection of polished metal surfaces, and nonmetallic luster, which

includes pearly, resinous, silky, vitreous (or glassy), and waxy lusters. Luster is best described from fresh

and unweathered surfaces, and preferably from crystal faces. Weathered minerals are typically described as

earthy in luster.

Hardness

The hardness of a mineral refers to its resistance to scratching. It is a measure of the strength of the bonds

between the constituent atoms in a mineral: Minerals with relatively strong chemical bonds have greater

resistance to scratching and are thus harder than minerals with relatively weak chemical bonds.

The relative hardness of a mineral is measured by the Mohs scale of hardness, which was developed by the

German mineralogist Friedrich Mohs in the nineteenth century.

Cleavage

Cleavage describes the tendency of some minerals to break or split along flat surfaces called cleavage

planes. Cleavage planes are surfaces of weak chemical bonds in mineral crystals. For example, the

chemical bonds in muscovite, which has a sheet structure, are strong within the planes of the silicate sheets

but weak between them. This causes muscovite crystals to cleave well into thin sheets which can be peeled

away like layers of an onion.

Some minerals such as mica, feldspar, and fluorite have good to excellent cleavage in one, two, three, four,

or even six different directions, and they cleave cleanly to form regular geometric shapes with smooth

cleavage planes.

Fracture

Fractures are rough nonplanar breaks which cut randomly through mineral crystals. Minerals fracture

rather than cleave whenever the bonds between their constituent atoms are equally strong in all directions,

so that there are no preferred planes of weakness in their structures.

Fractures are very common to the framework silicates such as quartz, which exhibits distinct smooth,

concentric, dish-shaped conchoidal fracture patterns. Other patterns include fibrous, which describes a

wood-like splintery fracture, and uneven, which describes a rough and irregular fracture.

Color and Streak

The color of a mineral is one of its most obvious properties, but it is not always diagnostic. The color of a

mineral can be greatly affected by trace amounts of chemical impurities. For example, quartz (SiO2) is

light colored and transparent, but amethyst is a variety of quartz which is tinted purple by traces of iron.

Fortunately, there are many minerals (particularly the oxide, sulfide, native metal, and hydroxide minerals)

which are not affected in this way and can be recognized on the basis of their colors. The best way to

examine the color of such minerals is to grind them against a streak plate of unglazed porcelain and

examine the color of the powder trace which the mineral leaves behind.

Specific Gravity

Specific gravity is defined as the ratio of the weight of a mineral to the weight of an equal volume of

water. It is essentially a measure of the density of a mineral and thus reflects its chemical composition. The

specific gravity of a mineral can be measured precisely in a laboratory, and it can be estimated by feeling

the heft of the mineral.

Other Properties

There are several other properties which are diagnostic of specific minerals.

Effervescence describes the reactivity of minerals to dilute hydrochloric acid (HCl). This "acid test" is a

diagnostic property of carbonate minerals such as calcite and dolomite.

Magnetism is attraction to magnets, steel paper clips, and other similar objects. It is diagnostic of the

mineral magnetite.

Lesson 3:

Goal: Students will be able to identify a mineral and explain each aspect of its definition, along

with identifying physical properties that allow us to identify them.

Motivation: Tell students that relatively few of the 3000 mineral’s found in the Earth’s

crust have economic value. However, these few minerals are widely used for a variety of

purposes. Have students write descriptions of seven objects around the classroom that

contain minerals or that were obtained from minerals.

NYS Standards:


structure.








temperature changes


pressure.


Connection: Compounds, chemical bonds – covalent, ionic, metallic, Van der Waal’s forces

Teach: Definition of minerals and physical properties, structure of molecule, silicon tetrahedron,

silicate structures (isolated, ring, single chains, double chains, sheets, framework)




Handout- Minerals

Shareout

Journal: What are the major mineral groups? Give a brief description of each

Homework: Due Friday: Research Report-

Choose 1 element, find a mineral that is composed of it and research info about the element

and the mineral (ex. Properties, chemical composition, etc.)

- Cover sheet

- 1-2 pages, single spaced, typed

Worth 1 test grade

Lesson 4:

Goal: Students should be able to successfully complete lab exercise on mineral identification in

preparation for Earth Science Regents. Students should be able to identify properties that are

related to mineral identification and be knowledgeable of different mineral groups.

Motivation: Students list properties related to given mineral samples. After making a list on

board, try to classify each type of description, leading into lesson of properties of mineral

classification

NYS Standards:


structure.








temperature changes


pressure.

St7 K2: Solving interdisciplinary problems involves a variety of skills and strategies, including

effective work habits; gathering and processing information; generating and analyzing ideas;

realizing ideas; making connections among the common themes of mathematics, science, and

technology; and presenting results.


Connection: Intro to minerals, structure of matter, mineral definition

Teach: Properties & techniques used in mineral identification

Model / Demonstrate: Illustrations

Student Engagement: Answer questions related to topic


Lab Exercise

Shareout

Journal: What are the mineral characteristics one looks for when identifying them?

Mineral Identification Lab

Directions: Go to http://mineral.galleries.com/default.htm. Click on Full Text Search

Use the characteristics below to try to identify each mineral. To search the database,

enter only the keywords in italics and read the descriptions of the minerals that match.

Each mineral has a list of Physical Characteristics that you should read and try to match

to the descriptions below.

(Hint: The characteristics of streak, hardness, and cleavage will help you to narrow

down your search!)

Mineral #1:

The color is black.

The luster is vitreous.

The fracture is conchoidal.

The streak is white.

The hardness is 5.

This mineral is:

Mineral #2:

The color is yellow.

The luster is resinous.


The streak is yellow.

The hardness is 2.

Other characteristics: Strong odor

This mineral is:

Mineral #3:

The color is white.

The luster is adamantine.



The hardness is 10.

The cleavage is perfect in 4 directions

This mineral is:

Mineral #4:

The color is black.

The luster is pearly.

The fracture is uneven.


The hardness is 2.5.

The cleavage is in one direction,

producing thin sheets or flakes.

This mineral is:

Mineral #5:

The color is gray.

The luster is dull.

The fracture is uneven.


The hardness is 1.

Other characteristics: Feels soapy.

This mineral is:

Mineral #6:

The color is black silver.

The luster is metallic.

http://mineral.galleries.com/default.htm

The fracture is flaky.

The streak is gray.


Other characteristics: Leaves black

marks on hands.

This mineral is:

Mineral #7:

The color is white.

The luster is vitreous.



The hardness is 3.

The cleavage is perfect in three

directions.

This mineral is:

Mineral #8:

The color is copper green.

The luster is metallic.

The fracture is jagged.

The streak is reddish.


This mineral is:

Compare the physical characteristics of Gold and Pyrite (also known as “fool’s

gold”). To find them, click on By Name at the top of any web page, then click on the

first letter of the mineral and find it listed in alphabetical order.

Gold:

The color is .

The luster is .

The fracture is .

The streak is .

The hardness is .

The cleavage is .

Pyrite:

The color is .

The luster is .

The fracture is .

The streak is .

The hardness is .

The cleavage is .

What major difference between the two would help you to identify if a mineral were…Gold

or Pyrite? Mineral Identification Lab

Grade Level: 6, 7, 8, 9, 10, 11, 12

Subject(s):

Science/Geology

Computer Science

Duration: Two 50-minute sessions

Description: Using the Amethyst Galleries, Inc. mineral database web site, students search for

minerals by entering the known characteristics, such as streak, hardness, color, etc. Since many

minerals share similar traits, there can be more than one correct answer. Finally, using what they

have learned about identifying minerals, the students are asked to identify the difference between

gold and pyrite.

Goals: Students will gain a deeper understanding of how scientists identify minerals, based on

the minerals' characteristics.

Objectives: Students will be able to:

1. find a mineral which matches each set of traits correctly.

2. determine the difference between gold and pyrite.

Materials:

Mineral Identification Worksheet

Vocabulary Handout

Worksheet and Handout in .pdf format; requires free Adobe Acrobat Reader.

computers with Internet access

Vocabulary: adamantine, cleavage, conchoidal, fracture, luster, metallic, Mohs scale, pyrite,

resinous, streak, and hardness

Procedure: Distribute the Mineral Identification worksheet and Vocabulary handout. Read the

directions for the identification activity, and review the vocabulary terms. Have students log on to

a computer and go to the web site (http://mineral.galleries.com/default.htm ).

Inform students to enter ONLY the words in italics to narrow their search. If a mineral matches

all of the criteria (such as streak, hardness, etc.) then it is a correct match! Each set of

characteristics can have one or more possible answers. Students should be able to search for the

characteristics of a known mineral (gold and pyrite) in order to answer the last question.

Assessment: If the minerals match ALL of the physical characteristics listed, then the student

was successful. Teachers may want to search the minerals ahead of time in order to make an

answer key, but be careful of duplicate answers.

http://www.eduref.org/Virtual/Lessons/Science/Geology/GLG0201a.pdf

http://www.eduref.org/Virtual/Lessons/Science/Geology/GLG0201b.pdf

(http:/mineral.galleries.com/default.htm

Useful Internet Resource: * The Mineral Gallery - A service of Amethyst Galleries, Inc.

A collection of mineral descriptions and images, searchable by name, class, and keyword.


Mineral Identification Lab

Vocabulary Terms

Adamantine: (ad"u-man'tEn), —adj. like a diamond in luster; ―sparkly.‖

Cleavage: (klE'vij), —n. The tendency of a mineral to split along specific planes,

determined by the crystal structure. Conchoidal: (kong-koid'l), —adj. a shell-like or spiral fracture produced on certain

minerals.

Fracture: (frak'chur), —n. the appearance of a broken surface

Luster: (lus'tur), —n. The manner in which light reflects from the surface of a mineral,

described by its quality and intensity.

Metallic: (mu-tal'ik), —adj. a luster resembling the surface of a metal.

Mohs scale: (mOz skAl), —n The ten-point scale of mineral hardness, based on the

minerals talc (1), gypsum (2), calcite (3), fluorite (4), apatite (5), orthoclase (6), quartz

(7), topaz (8), corundum (9), and diamond (10) in increasing order of hardness.

Pyrite: (pI'rIt), —n. a very common brass-yellow mineral, iron disulfide (FeS2) with a

metallic luster; commonly known as ―Fool’s Gold‖ due to it’s resemblance to gold.

Resinous: (rez'u-nus), —adj a ―powdery‖ luster.

Streak: (strEk), —n. The color of a mineral in its powdered form, usually obtained by

rubbing the mineral against an unglazed porcelain tile to see the mark it makes. A mineral

harder than the tile must be pulverized by crushing.

Hardness: (härd'nis), —n. Resistance of a mineral to scratching, determined by the Mohs

Scale.

Vitreous: (vi'trE-us), —adj. a luster resembling glass, as in transparency, glossiness, etc


Lesson 5:

Goal: Students should be able to identify ores and their uses, mines and gems. Students should be

able to identify mineral groups and where they are found in NYS and NJ.

Motivation: Divide class in groups and assign each group an ore to research on internet

(gold, zinc, iron, silver, aluminum, sulfur, tin, uranium)

NYS Standards:


structure.








temperature changes


pressure.


Connection: Intro to minerals, structure of matter, mineral definition, Properties & techniques

used in mineral identification

Teach: Ores, hematite, bauxite, rutile (titanium), mines, gems- uses of / value

Model / Demonstrate: Powerpoint, Illustrations



Pretend you are going on a field trip to quarry or mine. What questions would you ask the

person conducting the tour? (methods, safety, etc)

Shareout

Journal: What is an ore? What are the benefits to having mineral resources in our state?

Homework: Have students choose one mineral found in New York State and write a 1-

2page report on the mineral’s properties, where it is found/mined, what it is used for.

NEW YORK MINERALOGICAL CLUB - NEW YORK CITY MINERAL SPECIMENS

E-mail: [email protected] Dukelabs.com and

Dukelabs.com © 2001

Background: Over the past century plus, The New York Mineralogical Club has amassed a huge collection

of minerals, with donated specimens, purchased, collected, and bartered for by its members. The minerals

of New York City (NYC) were formed at great depth in the earth during and after primary high grade

metamorphism of their bedrock hosts. Various native metamorphic rocks that underlie the city, including

marble, quartzite, schist, gneiss, granofels, and amphibolite, show the effects of numerous phases of

mineralization. Commonly developed during metamorphic recrystallization, metasomatic reactions, along

faults and within contact zones of crosscutting igneous rocks, these historic mineral specimens were

collected (many over a hundred years ago) during construction of the city's infrastructure. They are a legacy

to the natural beauty of a now overdeveloped cosmopolitan area. Looking down the crowded streets and

avoiding speeding cabs, we can lose track of the slow, inexorable geologic development of our area or of

the effects of glaciers that recently (less than 12,000 years ago) honed the earth's surface.

In NYC, all of the bedrock units now exposed at the earth's surface, were subjected to two episodes of high

pressures and great, fusing temperatures, formerly existing in the depth range of 25-40 km (~15-25 miles).

The crystalline bedrock that forms the solid underpinning of New York's magnificent skyline has been

exhumed from these great formative depths. Controlled by the bulk chemistry of the host rocks and the

reactive chemical nutrients of penetrating active fluids, mineralization has left a trail marker of changed

geological conditions. They have resulted in formation and subsequent erosion of the Appalachian

mountains during roughly 1.1 Billion years of protracted Proterozoic and Paleozoic mountain building.

Geologists use mineral assemblages in rocks of the earth's crust in much the same way that a race-car driver

(or average NYC motorist, for that matter) would use an instrument cluster in their vehicle to gauge

performance. We, as geologists, use the textures- and minerals in rocks as "gauges" to estimate past

variations in strain patterns and changing crustal position in an effort to reconstruct ancient mountain

building events.

Comments below on the individual specimens are attached for educational purposes only and are the result

of carefully examining the specimens within the context of our decades of field examination of the bedrock

of NYC. The captions are written and copyrighted by Charles Merguerian of Duke Geological Laboratory

and are available for any not-for-profit educational purpose possible. We are indebted to the New York

Mineralogical Club and the American Museum of Natural History for permission to examine, photograph,

and "electronically" publish these images for all mineral collectors, and admirers of natural beauty to enjoy.

Titanite (Sphene) - Titanite, a

calcium titanium silicate is a

common accessory mineral in

amphibolite and marble of NYC.

The word sphene is derived from

the Greek word for wedge, an

allusion to the common habit of

the mineral. Here, green-colored

crystals are from amphibolitic

subunits of the Manhattan

formation in the Fort George area

of northern Manhattan. Kunz

Collection #587.

mailto:[email protected]

Beryl - Large beryl crystals are not

uncommon in granitoid dikes and veins

which crosscut the region. During WWII

huge amounts of New England beryl were

mined and stockpiled for the war effort as it

is an important light and strong metal for

avionics. Beryl, in its various forms

(aquamarine, emerald, heliodor, morganite)

is also utilized as a gemstone. This specimen

of greenish-blue beryl was found at 157th

Street and Broadway. Manchester Collection

# 1227.

Chrysoberyl - One of the more

spectacular specimens collected

from the bedrock of New York

City. Chrysoberyl is a rare,

complex beryllium

aluminosilicate that occurs in

granitic rocks and pegmatites and

in mica schist. This chrysoberyl

cluster is associated w/ smoky

quartz, garnet, plagioclase, and

kyanite (retrograded to muscovite

pseudomorphs). Used exclusively

as a gemstone, the varieties of

cymnophane and alexandrite are

of considerable value. Specimen

from 93rd Street and Riverside

Drive. Chamberlin Collection #690.

Black Tourmaline - Sprays of black tourmaline (schorl)

are commonly the result of boron-rich granitic vapors

seeping along small openings. This specimen from 170th

Street and Amsterdam Avenue. Kunz Collection #630.

Calcite - Large twinned

scalenohedron of calcite, a common

carbonate mineral but uncommon in

this size, from E.174th Street and G'D

Blvd., The Bronx. Manchester Collection #757.

Dumortierite - A rare borosilicate

pegmatite mineral found in

association with high temperature

metamorphism, dumortierite is

best known for its use in high-

grade porcelain (including spark

plug manufacture). Little known

from the east coast, important

deposits of dumortierite exist in

Rochester and Oreana, Nevada.

This blue fibrous, radiating

specimen, which is associated

with a quartz-, albite-, and K-spar

rich pegmatite, was found at 118th

Street and Fifth Avenue. A. C. Hawkins Loan #X-15.

Black Tourmaline - Throughout

New England, black-colored

tourmaline (variety schorl) is

found in association with

granitoid dikes and other small

injections into metamorphic

wallrocks. This specimen in

smoky quartz from 105th Street

and Fifth Avenue. Chamberlin

Collection #663.

Famous Kunz "Subway? or Sewer?" Garnet - Weighing in at roughly nine pounds and used for years as a door stop

at the Department of Public Works, this specimen is the most famous mineral specimen from Manhattan Island.

Rumored to have been found in an excavation for the subway system, according to an article by mineralogist John

Betts, the large garnet was found August 1885 by a laborer digging a sewer. Unknown is whether the garnet was

removed from a metamorphic host rock or whether it was found loose. Kunz Collection.

Almandine Garnet - A very common accessory mineral in the rocks of NYC. This specimen was found at 65th Street and Broadway. Kunz Collection #188.

Magnetite - A large octahedron of magnetite found at 176th Street and Broadway. Manchester Collection #1191.

Calcite - Nicely formed calcite crystals here found in a small cavity in schistose marble found near E.174th Street and G'D Blvd., The Bronx. Manchester Collection #757.

Beryl - Tapered green beryl crystals found in

aluminous schist of the Hartland Formation exposed

along 94th Street and Riverside Drive. Note the filled

fractures parallel to the basal cleavage of the crystals. J. A. Grenzig Collection #X-40, 1899.

Kyanite - A high pressure aluminosilicate mineral very common to the bedrock units of NYC. It occurs in nodules

intergrown with quartz and magnetite and in idioblastic clusters in quartz veins (as pictured here). Clearly similar in

quality to the famous Judd's Bridge locality in Connecticut, these crystals are partly replaced by muscovite (a

retrograde metamorphic effect). The specimen and its Hartland host rocks were found near 94th Street and Riverside Drive. J. A. Grenzig Collection, 1899.

Calcite - Found in association with the Inwood

Marble formation, these yellowish crystals were

found in a cavity in the Inwood Marble near 174th

Street and G'D Blvd., The Bronx. Manchester

Collection #750.

Kyanite - The phenomenal deep

blue color of this specimen is

atypical for kyanite found in

NYC. Similar to gemmy

specimens from Minas Gerais,

Brasil, this specimen, crystallized

in vein quartz, was located at 61st

Street and Central Park. E. Schernikow Collection #127.

Chabazite and Stilbite - Chabazite crystals (a

zeolite) roughly 1 cm on edge highlight this view of

gneissic rocks found at 45th Street and Second Avenue. Chamberlin Collection #107.

Beryl - Large interpenetrant beryl crystals, these

found at 190th Street and Amsterdam Avenue,

are commonly associated with granitoid dikes

and pegmatite. Kunz Collection #69.

Quartz - A phenomenal parallel-

growth crystal from The Bronx

found near Westchester Avenue.

Large crystals such as these are

found along fractures or faults. Barros Collection #18662.

Malacolite - An older term for

diopside, a calcic clinopyroxene.

Here a deep green euhedral

crystal (a porphyroblast) sits atop

crystalline marble. Unknown

locality but probably upper

Manhattan (Harlem Ship Canal?).

Manchester Collection #696.

Chrysotile - A dangerous member of the

serpentine group of minerals, fine high-aspect-ratio

acicular crystals of chrysotile are known irritants to

human lung- and stomach tissue. Prolonged

exposure can lead to lung cancer. As such, do not

breathe in to close to, or lick, your monitor on this

one! The result of metamorphism of ultramafic

rock, these matted crystals were collected at 81st

Street and Eighth Avenue. In the Hartland

formation, lenses of highly sheared serpentinite are

found. This "lost locality" may be genetically similar to chrysotile reported from Staten Island.

Stilbite - A member of the zeolite

group, this radiating specimen of

stilbite hails from 44th Street and

Second Avenue. Chamberlin Collection #562.

Stilbite - Scopiform stilbite crystals, again from the

vicinity of 45th Street between First and Second Avenue. Chamberlin Collection #582.

Titanite (Sphene) - Beautiful green-colored

"gemmy" crystals, similar to the very first

specimen above, are formed in amphibolite.

These specimens collected from 167th Street and

the Harlem River. E. Schernikow Collection.

Sphene - A common accessory mineral in

igneous and metamorphic rocks, this specimen of

sphene exhibits a dark-brown color in a schistose

host rock. from the Harlem Ship Canal. No other details.

Tourmaline - Interpenetrant

crystals of tourmaline (var.

schorl) collected from Hunt's

Point, The Bronx. NYC Department of Water Supply gift.

Lesson 6:

Goal: Students will review for test tomorrow.

Motivation: Get students into groups; Play “Mineral Baseball”

NYS Standards:


structure.








temperature changes


pressure.


Connection: Compounds, chemical bonds – covalent, ionic, metallic, Van der Waal’s forces

Teach: Definition of minerals and physical properties, structure of molecule, silicon tetrahedron,

silicate structures (isolated, ring, single chains, double chains, sheets, framework)




Students will work on review sheets in preparation for test.

Journal: Other than a diamond, which other mineral is useful for making a sandpaper

product? Why? Use ESRT for help.

Homework: Test Tomorrow

Lesson 7:

Goal: Students should be able to identify properties that are related to the rock cycle and be able

to explain how igneous rock is formed.

Standards:


structure.








temperature changes


pressure.

3.1c Rocks are usually composed of one or more minerals.

- Rocks are classified by their origin, mineral content, and texture.

- Conditions that existed when a rock formed can be inferred from the rock’s mineral content and

texture.

- The properties of rocks determine how they are used and also influence land usage by humans.


Connection: Properties & techniques used in mineral identification

Teach: Review rock Cycle, Igneous rocks- formation, melting processes, viscosity, Bowen’s

reaction series




Handout

Share (10-15 minutes)

Journal: Explain how igneous rock is formed.

Homework: Complete lab sheets which were due Monday

Read p. 52-61; make notes

p. 80 questions 1, 2, 3 on looseleaf

Igneous Rock Identification

Nature's Fiery Cauldron

The eruption of a volcano is an awesome process. Unfortunately, (or fortunately!) most of us will

never experience it in our lifetime. But we might have the opportunity to see the products of volcanic

processes while driving across country or hiking in the woods. Volcanic rocks, the solidified products

of volcanic eruptions are part of a larger group of rocks called igneous

rocks.

IGNEOUS ROCKS

Igneous rocks are crystalline or glassy rocks formed by the cooling and

solidification of molten magma. Igneous rocks comprise one of the three

principal classes of rocks, the others being metamorphic and sedimentary.

Igneous rocks are formed from the solidification of magma, which is a hot

(600 deg.C - 1300 deg.C, or 1100 deg. - 2400 deg. F) molten or partially

molten rock material. The Earth is composed predominantly of a large mass of igneous rock with a very

thin covering of sedimentary rock. Whereas sedimentary rocks are produced by processes operating mainly

at the Earth's surface such as weathering and erosion, igneous--and metamorphic--rocks are formed by

internal processes that cannot be directly observed.

Magma is thought to be generated within the asthenosphere (the layer of partially molten rock underlying

the Earth's crust) at a depth below about 60-100 kilometers (40-60 miles). Because magma is less dense

than the surrounding solid rocks, it rises toward the surface. It may settle within the crust or erupt at the

surface from a volcano as a lava flow. Rocks formed from the cooling and solidification of magma deep

within the crust are distinct from those erupted at the surface mainly owing to the differences in conditions

in the two environments. Within the Earth crust the temperatures and pressures are much higher than at its

surface; consequently, the hot magma cools slowly and crystallizes completely. The slow cooling promotes

the growth of minerals large enough to be identified visually without the aid of a microscope (called

phaneritic, from the Greek phaneros, meaning "visible"). On the other hand, magma erupted at the surface

is chilled so quickly that the individual minerals have little or no chance to grow. As a result, the rock is

either composed of minerals that can be seen only with the aid of a microscope (called aphanitic, from the

Greek aphanes, meaning "invisible") or contains no minerals at all (in the latter case, the rock is composed

of glass, which is really a viscous, non-crystalline liquid). This results in two groups of igneous rocks: (1)

plutonic or intrusive igneous rocks that solidified deep within the earth and (2) volcanic, or extrusive,

igneous rocks formed at the Earth's surface.

The deep-seated plutonic rocks can be exposed at the surface for study only after a long period of

weathering or by some tectonic forces that push the crust upward or by a combination of the two. The

exposed intrusive rocks are found in a variety of sizes, from small dikes to massive dome-shaped

batholiths, which cover hundreds of square miles and make up the cores of many mountain ranges.

Extrusive rocks occur in two forms: (1) as lava flows that flood the land surface much like a river and (2) as

fragmented pieces of magma of various sizes (pyroclastic materials), which often are blown through the

atmosphere and blanket the Earth's surface upon settling. The coarser pyroclastic materials accumulate

around the erupting volcano, but the finest pyroclasts can be found as thin layers located hundreds of miles

from the opening. Most lava flows do not travel far from the volcano, but some low-viscosity flows that

erupted from long fissures have accumulated in thick sequences. Both intrusive and extrusive magmas have

played a vital role in the spreading of the ocean basin, in the formation of the oceanic crust, and in the

formation of the continental margins. Igneous processes have been active since the formation of the Earth

some 4.6 billion years ago.

CLASSIFICATION

Igneous rocks are classified on the basis of mineralogy, and texture. As

discussed earlier, texture is used to subdivide igneous rocks into two major

groups: (1) the plutonic rocks, with mineral grain sizes that are visible to the

naked eye, and (2) the volcanic types, which are usually too fine-grained or

glassy for their mineral composition to be observed without the use of a

microscope. Being rather coarsely grained, phaneritic rocks readily lend themselves to a classification

based on mineralogy since their individual mineral components can be discerned, but the volcanic rocks are

more difficult to classify because either their mineral composition is not visible or the rock has not fully

crystallized owing to fast cooling.

A plutonic rock may be classified mineralogically based on the actual

proportion of the various minerals of which it is composed. In any

classification scheme, boundaries between classes are set arbitrarily;

however, if the boundaries can be placed closest to natural divisions

or gaps between classes, they will seem less random and subjective,

and the standards will facilitate universal understanding. The most

commonly used scheme was devised by the International Union of

Geological Sciences (IUGS)(See image).

While such a classification is desirable for petrologists, the average

earth scientist relies on a much simpler scheme. That classification

takes advantage of simple associations that occur among the various

silicate minerals. We do not need to know percentages of the various

mineral phases, merely which minerals are present. While not as

accurate or precise as the IUGS classification if is more than adequate

for field and lab studies. We will be utilizing this classification as our basis for identifying igneous rocks.

Volcanic rocks present a greater challenge. Since many of the mineral grains are not visible, using a

mineralogical classification becomes problematic. Ideally we would like to have a chemical analysis.

However, most lay people have little access to analytic facilities and a classification based on chemistry,

although desirable, is rather impractical. Thus, most field classifications of volcanic rocks rely on the few

phenocrysts we can see or the rock's color. The latter can be especially unreliable, but often it is the only

clue me have. We shall attempt to rely on texture, color and phenocryts to identify our volcanic rock

specimens.

Phaneritic Texture

Examples of Phaneritic Rocks (the

three images below show a hand sample,

low magnification of a hand sample and

a thin section of phaneritic textured

rocks)

Phaneritic textured rocks are comprised of large crystals that are clearly visible to the eye with or without a hand lens or binocular microscope. The entire rock is made up of large crystals, which are generally 1/2 mm to several centimeters in size; no fine matrix material is present. This texture forms by slow cooling of magma deep underground in the plutonic environment.

The cartoon sketch above, though highly idealized, attempts to make the point that in order to be truly phaneritic all of the mineral grains must be visible. The beginner often makes the mistake of identifying porphyritic textured (see discussion below) aphanitic rocks as phaneritic. For the more felsic rocks like granite, phaneritic texture is rarely misidentified. But dark rocks like gabrro are more problematic. A good rule of thumb is that fine grained or aphanitic rocks are dull appearing, while phaneritic rocks are brighter or shinier (of course be careful of a glassy rock like obsidian).

Examples of Phaneritic Rocks

Aphanitic Texture

Examples of Aphanitic Rocks

Aphanitic texture consists of small crystals that cannot be seen by the eye with or hand lens. The entire rock is made up of small crystals, which are generally less than 1/2 mm in size. This texture results from rapid cooling in volcanic or hypabyssal (shallow subsurface) environments.

Yes, I know the cartoon above is rather crude, but it gets the point across. Aphanitic rocks are characterized by textures in which the mineral grains are not visible to the eye so they generally look rather like a blank slate. Of course, this represents an ideal world. Most aphanitic rocks will have at least a few phenocrysts (larger grains). This often causes the lay person to assume a phaneritic texture, but with a little practice you will find you can quickly distinguish between aphanitic and phaneritic textures.

Examples of Aphanitic Rocks

Porphyritic Texture

Porphyritic Rocks (the two images

below show a hand sample and a thin

section of porphyritic aphanitic textured

rocks)

Porphyritic texture is really a subtype, but usage of the term often confuses the beginner. Porphyritic rocks are composed of at least two minerals having a conspicuous (large) difference in grain size. The larger grains are termed phenocrysts and the finer grains either matrix or groundmass (see the drawing below and image to the left). Porphyritic rocks are thought to have undergone two stages of cooling; one at depth where the larger phenocrysts formed and a second at or near the surface where the matrix grains crystallized.

Both aphanitic and phaneritic rocks can be porphyritic, but the former are far more common. Most often the porphritic term is utilized as a modifier. For instance, an andesite with visible phenocrysts of plagioclase feldspar would be termed an andesite porphyry or porphyritic andesite (see photo above).

Glassy Texture

Glassy textured igneous rocks are non-crystalline meaning the rock contains no mineral grains. Glass results from cooling that is so fast that minerals do not have a chance to crystallize. This may happen when magma or lava comes into quick contact with much cooler materials near the Earth's surface. Pure volcanic glass is known as obsidian (see photo).

Vesicular Texture

This term refers to vesicles (holes, pores, or cavities) within the igneous rock. Vesicles are the result of gas expansion (bubbles), which often occurs during volcanic eruptions. Pumice and scoria are common types of vesicular rocks. The image to the left shows a basalt with vesicles, hence the name "vesicular basalt".

Fragmental Texture

We are almost done, I promise. The last textural term is reserved for pyroclastic rocks, those blown out into the atmosphere during violent volcanic eruptiions. These rocks are collectively termed fragmental. If you examine a fragmental volcanic rock closely you can see why. You will note that it is comprised of numerous grains or fragments that have been welded together by the heat of volcanic eruption. If you run your fingers over the rock it will often feel grainy like sandpaper or a sedimentary rock. You might also spot shards of glass embedded in the rock. The terminology for fragmental rocks is voluminous, but most are simply identified as "tuff".

MINERALS OF IGNEOUS ROCKS To correctly classify many igneous rocks it is first necessary to identify the constituent minerals that make up the rock. Piece of cake you say, I saw most of these minerals when I did the Minerals Exercise or I have them in my mineral collection. Well, its not quite that easy. The mineral grains in rocks often look a bit different than the larger mineral specimens you see in lab or museum collections. The following section is meant to assist you in recognizing common rock-forming minerals in igneous rocks. Refer back to it often as you attempt to classify your rock specimens.

Plagioclase

Plagioclase: the white or chalky looking

grain is the common feldspar,

plagioclase.

Plagioclase is the most common mineral in igneous rocks. The illustration to the left shows a large chalky white grain of plagioclase. The chalky appearance is a result of weathering of plagioclase to clay and this can often be used to aid in identification. Most plagioclase appears frosty white to gray-white in igneous rocks, but in gabbro it can be dark gray to blue-gray. If you examine plagioclase with a hand lens or binocular microscope you can often see the stair-step like cleavage and possibly striations (parallel grooves) on some cleavage faces. Some potassium feldspar is white like plagioclase, but is usually a safe bet to identify any frosty white grains in igneous rocks as plagioclase. Expect to find plagioclase in most phaneritic igneous rocks and often as phenocryts in aphanitic rocks.

Quartz

Quartz: the dark gray, glassy grain is

quartz.

Quartz is also a very common mineral in some igneous rocks. It can be difficult to recognize since it doesn't look like the beautiful, clear hexagonal-shaped mineral we see in mineral collections or for sale in rock shops. In igneous rocks it is often medium to dark gray and has a rather amorphous shape. If you look at it with a hand lens you will notice the glassy appearance and lack of any smooth cleavage surfaces. You will also find quartz grains resist scratching with a nail or pocket knife, You can expect to find abundant quartz in granite and as phenocryts in the volcanic rock rhyolite. In some other common igneous rocks you may find a few scattered grains of quartz, but it is often conspicuous by its absence. Once recognized, quartz is rarely confused with any other common rock-forming mineral.

Potassium Feldspar

Orthoclase: the slightly pinkish grains

are the potassium feldspar, orthoclase.

Think pink is the motto for potassium feldspar. The image to the left shows several large grains of the potassium feldspar, orthoclase; note the pinkish cast. As orthoclase is a feldspar, you should also see the stair-step cleavage characteristic of feldspars. Unfortunately, all potassium feldspar is not pink, microcline is usually white. How does one distinguish white potassium feldspar from plagioclase? The answer is that in hand samples it is nearly impossible. Sometimes striations on cleavage faces allow you to differentiate the two. Plagioclase has striations, potassium feldspar does not. But in most cases any white feldspar is identified as plagioclase and any pink feldspar as orthoclase. Expect to find orthoclase as a common constituent of granite and matrix material in rhyolite. In the latter rock the orthoclase is too fine-grained to be seen even with a binocular microscope, but its presence gives most rhyolites a distinct pinkish cast.

Muscovite

Muscovite: the small, shiny grains are

muscovite.

Muscovite is not a common mineral in igneous rocks, but rather an accessory that occurs in small amounts. It is shiny and silvery, but oxidizes to look almost golden. In fact, more prospectors probably confused muscovite in their pans for gold than they did pyrite (fool's gold). Muscovite has excellent cleavage and will scratch easily. If you suspect muscovite is present, try taking a nail to it. It should flake off the rock. Muscovite occurs in some granites and occasionally in diorite. Unlike, its close cousin, biotite, it rarely occurs as phenocrysts in volcanic rocks.

Biotite

Biotite: the small, black grains are

biotite.

Biotite occurs in small amounts in many igneous rocks. It is black, shiny and often occurs in small hexagonal (6-sided) books. Unfortunately, it is often confused with amphibole and pyroxene. Like muscovite, it is soft and has good cleavage. Try scratching the black grains with a nail or knife. Biotite will flake off easily. Biotite is differentiated from amphibole by shape of the crystals (hexagonal for biotite and elongated or needle-like for amphibole) and by hardness (biotite is soft, amphibole is hard). It is differentiated from pyroxene by hardness, color (biotite is black and pyroxene dark green) and occurrence (biotite is found in light-colored igneous rocks like granites, diorites and rhyolites while pyroxene occurs in dark-colored rocks like gabbro and basalt). Expect to find biotite as a common accessory in granite, and as phenocrysts in some rhyolites.

Amphibole

Amphibole: the elongated, black grains

are amphibole.

Amphibole is a rather common mineral in all igneous rocks, however, it is only abundant in the intermediate igneous rocks. It occurs as slender needle-like crystals (see image to the left). It has good cleavage in 2 directions and hence has a stair-step appearance under a binocular microscope. It is often confused with biotite and pyroxene. Biotite is softer and the needle-like crystals differentiate it from pyroxene. One caution, most students believe that all amphibole crystals must have the pencil-like appearance. Remember the orientation of grains in an igneous rock is random. What would your pencil look like if you looked at it down the eraser? Not all grains of amphibole will be oriented so you can see the elongation of the crystals. Its a good guess that if you see a few crystals that have the "classic" amphibole shape, the other black grains are also amphibole. Biotite and amphibole do occur together in igneous rocks, but the association is not all that common. Amphibole is very commom in diorite, less so in granite or gabbro. It also is a common and diagnostic phenocryst in andesite.

Pyroxene

Pyroxene: the equi-dimensional, green

grains are pyroxene.

Pyroxene is common only in mafic igneous rocks. It occurs as short, stubby, dark green crystals (see image to the left). It has poor cleavage in 2 directions and cleavage surfaces are often hard to see with even a binocular microscope. It is often confused with biotite and amphibole. Biotite is softer, darker and occurs in predominantly light-colored rocks Amphibole is also darker and occurs in needle-like crystals rather than the stubby shape of pyroxene. Association is the best guide for the identification of pyroexene. It is usually restricted to dark-colored rocks (the image on the left is of pyroxene is a very rare light-colored rock called shonkenite) such as gabbro or basalt.

Olivine

Olivine: the green, glassy grains are

olivine.

Olivine is common only in ultramafic igneous rocks like dunite and peridotite. It occurs as small, light green, glassy crystals (see image to the left). It has no cleavage. The texture of olivine in igneous rocks is often termed sugary. Run your fingers over the grains, do they feel like sandpaper? The mineral is most probably olivine. Although olivine occurs in gabbro and basalt, it is far more common in peridotite and dunite. Because of the light green color and sugary texture it is rarely confuded with other rock-forming minerals.

CLASSIFICATION OF IGNEOUS ROCKS

The classification of igneous rocks has been the subject of frequent debate and voluminous literature. Over the past decade, most geologists have accepted the IUGS (International Union of the Geological Sciences) classification as the standard. Since this classification is being widely adopted, it bears discussion. However, as we shall see is rather complex and best left to advanced students. For our purposes, we will introduce and discuss a much simpler classification that will allow us to easily identify the more common igneous rocks.

Igneous rocks are classified on the basis of mineralogy, chemistry, and texture. As discussed earlier, texture is used to subdivide igneous rocks into two major groups: (1) the plutonic rocks, with mineral grain sizes that are visible to the naked eye, and (2) the volcanic rocks, which are usually too fine-grained or glassy for their mineral composition to be observed without the use of a petrographic microscope. As noted in the sidebar to the left, this is largely a genetic classification based on the depth of origin of the rock (volcanic at or near the surface, and plutonic at depth). Remember that porphyritic rocks have spent time in both worlds. Let's first examine the classification of plutonic rocks.

A plutonic rock may be classified mineralogically based on the actual proportion of the various minerals of which it is composed (called the mode). In any classification scheme, boundaries between classes are set arbitrarily. The International Union of Geological Sciences (IUGS) Subcommission on the Systematics of Igneous Rocks in 1973 suggested the use of the modal composition for all plutonic igneous rocks with a color index less than 90 (Image to the right). A second scheme (not shown) was proposed for those plutonic ultramafic rocks with a color index greater than 90.

The plotting of rock modes on these triangular diagrams is simpler than it may appear. The three components, Q (quartz) + A (alkali (Na-K) feldspar) + P (plagioclase), are recalculated from the mode to sum to 100 percent. Each component is represented by the corners of the equilateral triangle, the length of whose sides are divided into 100 equal parts. Any composition plotting at a corner, therefore, has a mode of 100 percent of the corresponding component. Any point on the sides of the triangle represents a mode composed of the two adjacent corner components. For example, a rock with 60 percent Q and 40 percent A will plot on the QA side at a location 60 percent of the distance from A to Q. A rock containing all three components will plot within the triangle. Since the sides of the triangle are divided into 100 parts, a rock having a mode of 20 percent Q and 80 percent A + P (in unknown proportions for the moment) will plot on the line that parallels the AP side and lies 20 percent of the distance toward Q from the side AP. If this same rock has 30 percent P and 50 percent A, the rock mode will plot at the intersection of the 20 percent Q line described above, with a line paralleling the QA side at a distance 30 percent toward P from the QA side. The third intersecting line for the point is necessarily the line paralleling the QP side at 50 percent of the distance from the side QP toward A. A rock with 25 percent Q, 35 percent P, and 40 percent A plots in the granite field, whereas one with 25 percent Q, 60 percent P, and 15 percent A plots in the granodiorite field. The latter is close to the average composition of the continental crust of the Earth.

Ideally it would be preferable to use the same modal scheme for volcanic rocks. However, owing to the aphanitic texture of volcanic rocks, their modes cannot be readily determined; consequently, a chemical classification is widely accepted and employed by most petrologists. One popular scheme is based on the use of both chemical components and normative mineralogy. Because most lay people have little access to analytic facilities that yield igneous rock compositions, only an outline will be presented here in order to provide an appreciation for the classification scheme.

The major division of volcanic rocks is based on the alkali (soda + potash) and silica contents, which yield two groups, the subalkaline and alkaline rocks. Furthermore as they are so common, the subalkaline rocks have two divisions based mainly on the iron content with the iron-rich group called the tholeiitic series and the iron-poor group called calc-alkaline. The former group is most commonly found along the oceanic ridges and on the ocean floor and is usually

restricted to mafic igneous rocks like basalt and gabbro; the latter group is characteristic of the volcanic regions of the continental margins (convergent, or destructive, plate boundaries) and is comprised of a much more diverse suite of rocks.

Chemically the subalkaline rocks are saturated with respect to silica. This chemical property is reflected in the mode of the mafic members that have two pyroxenes, hypersthene and augite [Ca(Mg, Fe)Si2O6], and perhaps quartz. Plagioclase is common in phenocrysts, but it can also occur in the matrix along with the pyroxenes. In addition to the differences in iron content between the tholeiitic and calc-alkaline series, the latter has a higher alumina content (16 to 20 percent), and the range in silica content is larger (48 to 75 percent compared to 45 to 63 percent for the former). Hornblende and biotite phenocrysts are common in calc-alkaline andesites and dacites but are lacking in the tholeiites. Dacites and rhyolites commonly have phenocrysts of plagioclase, alkali feldspar (usually sanidine), and quartz in a glassy matrix. Hornblende and plagioclase phenocrysts are more widespread in dacites than in rhyolites, which have more biotite and alkali feldspar.

The alkaline rocks typically are chemically undersaturated with respect to silica; hence, they have only one pyroxene, the calcium-rich augite) and lack quartz but often have a feldspathoid mineral, nepheline. Microscopic examination of alkali olivine basalts (the most common alkaline rock) usually reveals phenocrysts of olivine, one pyroxene (augite), plagioclase and perhaps nepheline.

A Field Classification

Now that we have completely confused you,let's look at a much simpler classification. We call this a field classification because it requires little detailed knowledge of rocks and can be easily applied to any igneous rock we might pick up while on a field trip. It utilizes texture, mineralogy and color. The latter is a particularly unreliable property, but the classification realizes that certain fine-grained (aphanitic) igneous rocks contain no visible mineral grains and in their absence color is the only other available property. Students the thus cautioned to use color only as a last resort.

To employ this classification we must first determine the rock's texture. You might remember we have five basic textures; phaneritic (coarse), aphanitic (fine), vesicular, glassy and fragmental (our classification doesn't bother with the latter because we often term all fragmental igneous rocks tuffs). Examine your rock and determine which textural group it belows to. If it is glassy, vesicular or fragmental you cannot determine mineralogy and hence the name is simply obsidian for a glass, tuff for a fragmental or pumice/scoria for a vesicular rock (the latter are differentiated on the basis or color and size of the vesicles or holes).

For the phaneritic and some aphanitic rocks you must determine the mineralogy. Often it is only necessary to identify one or two key minerals, not all of the minerals in the rock. For instance quartz and potassium feldspar (k-feldspar) are restricted to granites and rhyolites. Amphibole is only abundant in diorite or andesite, although minor amounts can be present in granite. How am I getting these names? Let's take an example. I pick up my first specimen and notice that it is distinctly coarse grained (phaneritic). This means that it must be one of the rocks in the row labeled coarse (i.e., granite, diorite, gabbro or peridotite). I next place the rock under a binocular microscope and identify the minerals plagioclase and pyroxene. I go to the bottom row of the chart (Minerals Present) and look for a match with my mineralogy. I find it in the third column (Ca-play, pyroxene) and read the name (gabbro) from the coarse row on the chart. Pretty simple!! Relax, when you actually begin your igneous rock identification we will walk you through it step by step. But remember to refer to the above classification diagram often as an aid.

Academy of Finance and Enterprise

Lab Experiment

Mrs. Yiatrou

Name: _______________________ Date: ______________ Period: _______________

Crystal Growth

Magma forms deep within the Earth’s surface at depths of 25 to 160 km and at extremely

high temperatures. Some magma reaches the surface and cools quickly. Other magma

gets trapped in cracks or magma chambers deep below the surface and cools very slowly.

When magma cools slowly, large, well-developed crystals form. On the other hand,

when magma erupts onto the surface, heat is lost rapidly to the air or water. There is not

enough time for large crystals to grow. The size of the crystals found in igneous rocks

give geologists clues about where and how crystals are formed.

In this experiment, you will demonstrate how the rate of cooling affects the size of

crystals in igneous rocks by cooling crystals of magnesium sulfate at two different rates.

Materials:

- 400ml beaker - Magnesium sulfate - Aluminum foil

- 200ml of tap water - Hand lens - Test tube tongs

- Hot plate - Laboratory scoop - Labels

- Celsius thermometer - distilled water

Make a Prediction:

Suppose you had two solutions that are identical in every way except for the temperature.

How will the temperature of a solution affect the size of the crystals and the rate at which

they form?

Make Observations:

1. Put on your gloves, apron, and goggles.

2. Fill the beaker half way with tap water. Place the beaker on the hot plate and let it

begin to warm. The temperature of the water should be between 40º and 50º C.

Caution: Make sure the hot plate is away from the edge of the lab table. 3. Examine two or three crystals of the magnesium sulfate with your hand lens. On

the attached piece of paper, describe the color, shape, luster, and other interesting

features of the crystals. Draw a sketch of the magnesium sulfate crystals.

Conduct an Experiment:

4. Use a scoop to fill the test tube halfway with the magnesium sulfate. Add an

equal amount of distilled water.

5. Hold the test tube in one hand and use one finger from your other hand to tap the

test tube gently. Observe the solution mixing as you continue to tap the test tube.

6. Place the test tube in the beaker of hot water and heat it for approximately 3

minutes. Caution: Be sure to direct the opening of the test tube away from

you and other students.

7. While the test tube is heating, shape you aluminum foil into two small boat-like

containers by doubling the foil and turning up each edge.

8. If all the magnesium sulfate is not dissolved after 3 minutes, tap the test tube

again and heat it for another 3 minutes. Caution: Use the test tube tongs to

handle the hot test tube. 9. Label one of your aluminum boats ―Sample 1‖ and place it on the hot plate. Turn

off the hot plate.

10. Label the other aluminum boat ―Sample 2‖ and place it on the lab table.

11. Using the test tube tongs, remove the test tube from the beaker of water and

evenly distribute the contents to each of your foil boats. Carefully pour the hot

water in the beaker down the drain. Do not move or disturb either of your foil

boats.

Make Observations:

Using your hand lens, carefully observe the foil boats. Record the time it takes for the

first crystals to appear.

Crystal-Formation Table

Crystal Formation Time Size & Appearance of Crystals Sketch of Crystals

Sample 1

Sample 2

If crystals have not formed in the boats before class is over, carefully place

the boats in a safe place. You may record the time in days instead of in

minutes.

When the crystals have formed in both boats, use the hand lens to carefully examine the

crystals.

Analyze the Results:

1. Was your prediction correct? Explain.

2. Compare the size and shape of the crystals in Samples 1 and 2 with the size and

shape of the crystals examines in Step 3. How do you think the formation of the

original crystals might have taken?

Answers:

1. Answers may vary. A correct prediction would state that a cool solution will

produce crystals more quickly than a warm solution. A correct prediction would

also state that the crystals produced in a warm solution will be much larger than

those produced in a cool solution.

2. Because the original crystals were small, students may conclude that they formed

quickly.

Lesson 8:

Goal: Students should be able to understand how volcanoes are formed and identify the different

types of volcanoes.

NYS Standards:

2.1k The outward transfer of Earth’s internal heat drives convective circulation in the

mantle that moves the lithospheric plates comprising Earth’s surface.

2.1l The lithosphere consists of separate plates that ride on the more fluid asthenosphere

and move slowly in relationship to one another, creating convergent, divergent, and transform

plate boundaries. These motions indicate Earth is a dynamic geologic system.

-These plate boundaries are the sites of most earthquakes, volcanoes, and young

mountain ranges.

- Compared to continental crust, ocean crust is thinner and denser. New ocean crust

continues to form at mid-ocean ridges.

- Earthquakes and volcanoes present geologic hazards to humans. Loss of property,

personal injury, and loss of life can be reduced by effective emergency preparedness.

2.1m Many processes of the rock cycle are consequences of plate dynamics. These include

the production of magma (and subsequent igneous rock formation and contact metamorphism)

at both subduction and rifting regions, regional metamorphism within subduction

zones, and the creation of major depositional basins through down-warping of the crust.

2.1n Many of Earth’s surface features such as mid-ocean ridges/rifts, trenches/subduction

zones/island arcs, mountain ranges (folded, faulted, and volcanic), hot spots, and

the magnetic and age patterns in surface bedrock are a consequence of forces associated

with plate motion and interaction.


Connection: Surface deformation

Teach: Intro to volcanoes

Model / Demonstrate: Illustrate on board, use text as reference, handout (diagrams)



Handout


Journal: What are the three things that affect magma formation?

Homework: Research and find examples of the different types of volcanoes

Handout:

Subject: Earth Science

Teacher: Mrs. Kalliangas

Topic: Volcanoes

I. Volcano

A. Magma

1. Mixture of molten rock, suspended mineral grains & dissolved gases deep

within the Earth’s crust

2. Formation of magma

a. Temperature – increases with depth beneath the Earth’s surface

b. Pressure – increases with depth; explains why most rock in

Earth’s lower crust & upper mantle do not form magma

c. Water – found in pore spaces of some rock & can be bound into

the crystal structure of some minerals; at any given pressure, a

wet mineral/rock will melt at lower temperature than the same

mineral/rock under dry conditions

3. Types of Magma

a. Basaltic

i. forms basalt; when rock in upper mantle melts; rises

relatively rapidly to Earth’s surface; low viscosity

(internal resistance to flow); contains small amounts of

dissolved gases & silica

ii. volcanoes erupt quietly

b. Andesitic

i. found along continental margins

ii. source material – oceanic crust/sediments

iii. 60% silica – intermediate viscosity; intermediate

eruptions

c. Rhyolitic

i. forms when molten rock rises & mixes with overlying

silica & water-rich continental crust

ii. high viscosity- inhibits movement

iii. resistance to flow along with large volume of gas

trapped in magma; volcanoes explosive

4. Viscosity

a. depends on temperature & composition

b. amount of silica increases viscosity

II. Intrusive Activity

A. Forces overlying rock apart & enters newly formed fissures

B. Causes blocks of rock to break off & sink into magma

C. Can melt the rock which it intrudes

III. Anatomy

A. Vent

- opening in the Earth’s crust through which lava erupts & flows onto the surface

B. Crater

- bowl-shaped depression; forms around central vent

C. Caldera

- large crater up to 50km in diameter that can form when the summit or side of a

volcano collapses into the magma chamber during or after an eruption

IV. Types of Volcanoes

A. Shield

1. mountain with broad, gently sloping sides & a nearly circular base

2. forms when layer upon layer of basaltic lava accumulates during non-

explosive eruptions

B. Cinder-cone

1. when material ejected high into the air falls back to Earth & piles up

around the vent

2. steep sides; small (less than 500km high)

3. magma contains water & silica than magma of shield volcanoes

4. more explosive

C. Composite

1. when layers of volcanic fragments alternate with lava

2. magma contains large amounts of silica, water & gases

3. violently explosive; potentially dangerous to humans & environment

V. Where do they occur

A. Convergent Volcanism

1. Circum-Pacific Belt

2. Mediterranean Belt

B. Divergent Volcanism

C. Hot Spots

- unusually hot areas in Earth’s mantle that is stationary for long periods of time

Lesson 9:

Goal: Students should be able to identify properties of and name given metamorphic rock

samples and explain how metamorphic rocks are formed.

Standards:


structure.








temperature changes


pressure.

3.1c Rocks are usually composed of one or more minerals.

- Rocks are classified by their origin, mineral content, and texture.

- Conditions that existed when a rock formed can be inferred from the rock’s mineral content and

texture.

- The properties of rocks determine how they are used and also influence land usage by humans.


Connection: Properties of metamorphic rocks, texture, composition, lo-grade/high-grade

metamorphism, foliation of rock, identification of parent rock

Teach: Procedure for lab




Handout


Journal: What property of the rock was most helpful when identifying it?

Homework: Complete lab sheet; quiz tomorrow

Lesson 10:

Goal: Students should understand how the process of weathering breaks down rocks and how

erosion is the process by which this weathered material is transported from one area to another.

Standard: S2.1s Weathering is the physical and chemical breakdown of rocks at or near Earth’s

surface. Soils are the result of weathering and biological activity over long periods of time.

S2.1.t Natural agents of erosion, generally driven by gravity, remove, transport, and deposit

weathered rock particles. Each agent of erosion produces distinctive changes in the material that

it transports and creates characteristic surface features and landscapes. In certain erosional

situations, loss of property, personal injury, and loss of life can be reduced by effective

emergency preparedness.

S2.1u The natural agents of erosion include: streams, glaciers, wave action, wind, mass

movement


Connection: In previous unit, weathering and erosion were introduced as factors in the

formation of rocks. We are going to go into further detail about each.

Teach: What is weathering and how does it differs from erosion?

What are the differences between mechanical, chemical and biological weathering?

What are factors that affect the rate of weathering?

Model / Demonstrate: Students will look at photos again and see if they can identify which shows

mechanical, chemical, biological weathering.

Student Engagement: See above


In groups, students will brainstorm different examples of weathering that they see on a day to day

basis or that they are knowledgeable of.

Share (10-15 minutes):

Students will share their results and the rest of the class will determine if they are examples of

weathering and if so what kind.

Journal:

Why is weathering important?

Homework:

Bring in an example of weathering (photo, visual) and give a brief description on looseleaf.

Lesson 11:

Goal: Students should understand how the process of weathering and erosion play a role in the

formation of sedimentary rock and how this rock is classified.

Standard: S2.1s Weathering is the physical and chemical breakdown of rocks at or near Earth’s

surface. Soils are the result of weathering and biological activity over long periods of time.

2.1v Patterns of deposition result from a loss of energy within the transporting system and are

influenced by the size, shape, and density of the transported particles. Sediment deposits may be

sorted or unsorted.

2.1w Sediments of inorganic and organic origin often accumulate in depositional environments.

Sedimentary rocks form when sediments are compacted and/or cemented after burial or as the

result of chemical precipitation from seawater.


Connection: In previous unit, weathering and erosion were introduced as factors in the

formation of rocks. What is weathering and how does it differs from erosion?

What are the differences between mechanical, chemical and biological weathering?

What are factors that affect the rate of weathering?

Teach: Formation of sedimentary rocks, clastic vs. chemical, bioclastic, refer to reference tables

Model / Demonstrate: Students will look at rocks again and see if they can identify which shows

mechanical, chemical, biological weathering.

Student Engagement: See above


Brainstorm ways in which sedimentary rock can be helpful to scientists

Share (10-15 minutes):

Journal:

Compare and contrast clastic and chemical sedimentary rock

Homework:

Read p. 61-69 notes; answer questions 6-11 p. 80 (Review)

Academy of Finance & Enterprise EARTH SCIENCE

Mrs. Kalliangas

Name: __________________

Date: ___________________

Period: __________________

MINERALS & ROCKS LABORATORY

INTRODUCTION

The identification of minerals and rocks is an integral part of understanding our

physical environment. In order to comprehend and explain certain aspects of

geology, it is necessary to gain some familiarity with the characteristics of minerals

and rocks. Minerals and rocks exhibit a number of diagnostic properties which are

used for identification. Understanding these properties will help you describe and

identify minerals and rocks.

PURPOSE

The purpose of this laboratory exercise is to gain some familiarity with the mineral

and rock identification process. By doing so, you should be able to better understand

the basic principles of minerals and rocks and how they apply to one another.

Understanding the basics of minerals and rocks will serve as a foundation in learning

the introductory principles of geology.

BASIC DEFINITIONS

A mineral is a naturally occurring inorganic substance with a characteristic chemical

composition and definite crystal structure. The composition and crystalline structure

determines the properties of a mineral. The main mineral properties used for

identification are color, streak, hardness, specific gravity, cleavage and fracture.

Other properties such as luster and habit are also important.

Rocks are aggregates of minerals. Rocks exhibit not only different mixture of

minerals, but also certain textures. The texture depends upon the size, shape, and

arrangement of the minerals composing the rock. Mineral assemblage and texture

serve in determining the origin and identification of a rock.

MINERAL IDENTIFICATION PROCESS

MINERAL PROPERTIES

COLOR - The color of a mineral serves to narrow down the number

of possible choices since it is the first and most obvious

property noticed. However, because most minerals may

exhibit a variety of colors, color is not a reliable diagnostic property.

HARDNESS - Hardness is a measure of resistance to scratching. The hardness of a

mineral is based upon comparisons of scratching tests. Mohs Scale of Hardness is the

basic comparison test.

Mohs Hardness Scale Hardness of Test Materials

1 - Talc 2.5 - Fingernail

2 - Gypsum 3.5 - Copper penny

3 - Calcite 5.5 - Masonry nail

4 - Fluorite 5.5 - Glass

5 - Apatite

6 - Orthoclase feldspar

7 - Quartz

8 - Topaz

9 - Corrundum 10 - Diamond

Example of hardness determination: If an unknown mineral cannot be scratched by a

masonry nail but can be scratched by orthoclase feldspar, then the hardness of the unknown mineral would be between 5.6 and 5.9.

STREAK - The color of the powder of a mineral is the streak. Rub the mineral on a

piece of unglazed porcelain (streak plate) to obtain the streak.

CLEAVAGE - Certain minerals have a tendency to part, producing smooth flat

surfaces. An example is mica: it cleaves along one plane thus it has one direction of

cleavage. Galena breaks into cubes; a cube has three directions of cleavage that intersect at 90 degree angles.

FRACTURE - If a crystal does not break along a cleavage surface, it exhibits fracture.

Quartz shows no cleavage when it is broken, instead it fractures in a shell shape

known as conchoidal fracture. Other minerals with well-developed cleavage may

fracture along other surfaces. Common descriptions: conchoidal, splintery, fibrous and irregular.

LUSTER - The degree or manner in which the surface of a mineral reflects light is

luster. Terms used to describe luster include earthy, glossy, metallic, pearly, greasy, waxy, and vitreous (glassy).

SPECIFIC GRAVITY - The weight of a mineral compared to the weight of an equal

volume of water is the specific gravity. Gold has a specific gravity of 19. This

indicates that a cubic centimeter of gold weighs 19 times as much as a cubic

centimeter of water. (One cubic centimeter of water weighs 1.0 grams) A relative comparison (of what is light and what is heavy) is satisfactory for this laboratory.

DIRECTIONS FOR MINERAL IDENTIFICATION

An unknown mineral will be given a specimen number.

Use the mineral identification charts located in your ERST for reference.

On your worksheet, identify the following:

Color: The visible color. Hardness: The approximate hardness by comparing scratch tests. Streak: The color of the powder of the mineral by rubbing the mineral on the

the streak plate. Cleavage: The number of directions of cleavage and the angle of intersection,

if cleavage occurs. Fracture: The type of fracture, if it occurs. Luster: The type of luster the mineral exhibits. Specific Gravity: The relative weight of the mineral (very light, light, medium,

heavy, very heavy).

Remember the purpose of this exercise is for you not to necessarily identify the right

mineral (although it would be beneficial) but for you to understand the identification

process by using the diagnostic properties. Thus, when you are in a field

environment, you will be able to identify unknown minerals by using the diagnostic properties that were learned.

ROCK IDENTIFICATION PROCESS

COMPARING IGNEOUS, SEDIMENTARY, AND METAMORPHIC ROCKS

Each of the three rock types has a unique appearance that helps to distinguish one

type from another.

IGNEOUS ROCKS

Igneous rocks are made up of intergrown mineral crystals formed by the cooling of

magma or lava. Igneous rocks are classified using three attributes: the mineral composition, their texture, and color index.

The texture of igneous rocks is very useful in identifying unknown rocks. Those

igneous rocks with large crystals (crystals seen with the naked eye) are termed

phaneritic and are intrusive. Those igneous rocks with small crystals (crystals that

cannot be seen with the naked eye) are termed aphanitic and are extrusive. The

texture or the size of the crystals within a rock are determined by the rate of cooling

of magma or lava. Rapid cooling produces very small crystals while slow cooling

allows larger crystals to form. For this lab, the relative size of the crystals, either visible or not, is satisfactory.

The mineral composition (type and percentage) is a specific indicator. This does not have to be applied to this exercise due to its complexity.

Color index refers to relative terms used in identifying rocks. They are light, intermediate, and dark.

SEDIMENTARY ROCKS

Sedimentary rocks are made up of lithified sediments or precipitated materials.

Sedimentary rocks can be distinguished from igneous and metamorphic rocks since

they form in layers or strata. Another key feature that sets them apart is their fossil content. Fossils are rarely found in igneous and metamorphic rocks.

Sedimentary rocks can be classified by three important factors. (1) Detrital or clastic

rocks containing particles from pre-existing rocks, which are divided by particle size

and assortment. (2) The term organic indicates that the rock is made from shells or

other fossil fragments, silica based mineralization (chert), carbonaceous

development (limestone) or carbon based development (coal). (3) The term chemical indicates the minerals were produced by chemical precipitation.

METAMORPHIC ROCKS

Metamorphic rocks are rocks that have been altered and deformed physically and/or chemically by heat and pressure.

Metamorphic rocks can have foliated or non-foliated textures. Foliated textures

contain foliation or parallel planes of platy minerals. Non-foliated textures do not

contain any foliation, but do exhibit alterations such as the obliteration of mineral grains.

NOTE: CONSULT YOUR TEXT FOR FURTHER DISCUSSION OF THE DIFFERENCES BETWEEN IGNEOUS, SEDIMENTARY AND METAMORPHIC ROCKS.

DIRECTIONS FOR ROCK IDENTIFICATION

Use the rock identification charts located in your ERST.

On your worksheet identify the following:

For igneous rocks: Texture (large or small crystals)

Color (light, intermediate, dark)

For sedimentary rocks: Grain size (small, medium, large) Grain shape (rounded, angular)

For metamorphic rocks: Foliated or Non-foliated

Handouts:

- Outlines of lessons of the day

http://www.geol.umd.edu/~jmerck/geol100/lectures/25.html

Worksheets & labs from following sites:

http://www.newyorkscienceteacher.com/sci/files/media2.php?media=lab&subject=earth%20scien

ce

http://pbisotopes.ess.sunysb.edu/reports/ny-city/index.html

http://www.teachervision.fen.com/

http://www.lessonplanet.com/

Videos:

http://www.teachersdomain.org/

http://science.howstuffworks.com/

http://science.nationalgeographic.com/science/earth/inside-the-earth/rocks-article.html

http://www.geol.umd.edu/~jmerck/geol100/lectures/25.html

http://www.newyorkscienceteacher.com/sci/files/media2.php?media=lab&subject=earth%20science

http://www.newyorkscienceteacher.com/sci/files/media2.php?media=lab&subject=earth%20science

http://pbisotopes.ess.sunysb.edu/reports/ny-city/index.html

http://www.teachervision.fen.com/

http://www.lessonplanet.com/

http://www.teachersdomain.org/

http://science.howstuffworks.com/

http://science.nationalgeographic.com/science/earth/inside-the-earth/rocks-article.html

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