UNIT II

Rocks, Minerals,

& Resources

Presentation created by Mr. Elliott from Fort Plain Central School. Modified by Mr. Oliver Summer 2012.

Mineral Display at

American Museum of

Natural History in NYC

Start Unit II Objective Page Don’t forget to leave a column for dates.

• #1. What are minerals and describe their

characteristics?

• #2. Describe properties of minerals

including the seven basic physical

properties of minerals.

(ESRT p.16)

Introduction

• Lithosphere

– includes crust and small portion of upper

mantle

– Made of solid materials called rock.

• Building blocks of rock are called minerals.

• Rocks composed of single mineral called

monomineralic.

• Rocks composed of many minerals called

polymineralic.

Polymineralic Rock

Monomineralic Rock

Rock Salt

(made of halite only).

_________________________

_________________________

_________________________

_________________________

_________________________

_________________________

• *Mineral: Naturally formed material made up of one or more elements.

In order for a material to be a mineral it must be (have):

Naturally occurring

Inorganic (not from a living thing)

Crystalline

Solid material with definite shape

Definite Molecular structure

Specific physical properties

There are over 2,400 minerals that have been identified on Earth! Of

these, there are about a dozen of them that are so abundant that they

make up more than 90% of the Lithosphere. These very abundant

minerals are called the “rock formers”.

A. Minerals

•Minerals are made up of elements.

•Element: A substance composed of atoms which can

not be broken down into a more simple substance.

•Some minerals are made up of only one element but

most are made up of two or more elements and are

called compounds.

*Native Element Minerals: Minerals that occur in nature as single elements.

(Ex. Gold, iron, graphite, diamond, sulfur)

Halite (compound)

Diamond (only 1

element carbon)

ESRT p.16

Chart from cover (p.1) of ESRT

Be careful as % by

mass and volume

aren’t the same!

*A Minerals physical properties

are determined by its:

Internal arrangement of atoms!

aka: bonding or atomic structure

Internal structure of Halite

II. Physical and Chemical

Properties

The identification of minerals is done on the basis of well

defined physical and chemical properties

Physical Properties: ________________ Things you can see. Chemical Properties: _____________________________

______________ How a certain substance reacts with

other substances. Also includes: ________________________________ Things associated with atomic structure.

Carbon Atoms

(Graphite and Diamond)

Silica Tetrahedron

Mineral Review

*A. Color:

Unreliable for two reasons:

1. _______________________________

• Ex: ______________

Different minerals are the same color.

and Halite calcite

2. _____________________________ One mineral may have many colors.

Only a small impurity can easily change the mineral color.

• Ex: ______ Calcite or classroom samples of quartz

B. Streak: _______________________________ The color of a mineral in powder form.

• We do a streak test using a __________ (an unglazed

piece of porcelain tile)

Streak plate

Note: The color of a mineral may be very different than

the streak.

Streak is: _______________________ More reliable than the color.

*

*

Streak (not listed for

all minerals)

C. Hardness: __________________________________ Resistance of a mineral to being scratched.

• A hard mineral will make a scratch on a softer mineral

• To compare the hardness of minerals, scientists have

developed a scale called the: __________________ Moh’s scale of hardness.

• This scale also: ________________________________ compares hardness of common objects

*

(Feldspar)

(Iron nail)

(Streak plate)

a) Metallic: _________________________ If a mineral shines like a metal.

• Ex: ________________________ Galena, Magnetite, and Pyrite

b) Nonmetallic: _______________________________ If a mineral does not look like a metal.

• Ex: __________________________________ Glassy, Waxy, Greasy, Earthy, Dull, etc…

• Luster can either be metallic or nonmetallic.

The appearance of light reflected from a mineral’s

surface. D. Luster: _________________________________________

_______

Examples of Nonmetallic Luster

Earthy Glassy

Waxy

Dull

These zones of weakness appear as smooth planes or surfaces.

Cleavage: The tendency of a mineral to break along zones

of weakness or flat sides.

E: Cleavage vs. Fracture

Fracture: breaking unevenly, no definite cleavage.

Beryl (Aquamarine)

Basal Cleavage

(One directional)

Ex: Mica

Rhombic Cleavage

(three directional not

at right angles)

Ex: Calcite

Cubic Cleavage

(three directional

at right angles)

Ex: Halite

Conchoidal Fracture

Ex: Obsidian

Remember: If a mineral breaks

evenly with cleavage or unevenly

with fracture depends on the

internal arrangement of its atoms.

The geometric shape of a mineral due to its

internal arrangement of atoms.

F. Crystal Forms: ________________________________

_______________________________

*

G. Specific Gravity: _____________________________________

___________________

The ratio of the density of a mineral compared

To the density of water

•The Density of pure water is 1g/cc .

•So, if a mineral had a specific gravity of 3, the density of the

mineral would be: ____. 3 g/cc

= 3 g/cc 1 g/cc

Divide density

of mineral by

density of water

3 g/cc 1 g/cc

Units cancel

= 3

Specific gravity

of mineral

What is going on mathematically?

So specific gravity is just like density, but

with no units…

*

Calcite Reacts with Acid: When HCl is placed on a

clean surface, it gives off bubbles of CO2 .

Carbonates react

with dilute HCl and

other acids by

fizzing or bubbling

(releasing CO2 gas)

H) Special Properties of Some Minerals

Magnetite exhibits magnetic properties.

Halite tastes like salt

Talc feels slippery.

Talcum Powder

Fluorescence: Mineral emits visible light when

illuminated with high energy light

(ultraviolet).

Phosphorescence: Mineral emits visible light

even after ultraviolet light is switched

off. (glows in the dark.)

• Crystalline- atoms inside are bonded in a

particular pattern or structure

– Depends on “internal arrangement” of atoms

• Two minerals with the same chemical

composition but different crystal structure

may have very different properties.

a) Minerals are crystalline.

• Examples:

– Graphite and Diamond

• Both made of pure Carbon

• Different Bonding

• Graphite-weak bonds, very soft, used in pencils

• Diamond-strong bonds, very hard, jewelry/sawblades

Diamond

Graphite

• Another Example:

– Sand and Quartz or Glass

• Both composed of SiO2

• Different bonding, very different properties

Quartz

Quartz Sand

b) Minerals may be grouped according to the

elements of which they are made, or the

compounds which they can form.

• Examples:

– Oxides- oxygen with another element

– Carbonates- metal combined with CO3

(carbonate formula)

– Silicates- silicon bonded with oxygen

• Silicate formula- SiO4

• Silicate building block- tetrahedron

Iron oxide (rust)

Calcium carbonate

(limestone)

Cover of ESRT’s The two most abundant elements in Earth’s

crust by mass and volume are?

How many minerals in your ESRT’s contain both?

______________minerals are the most common on Earth! Silicate

Igneous Rock Objectives

• #3. How are igneous rocks formed? (ESRT p.6)

• #4. Describe how igneous rocks can be classified

according to either mineral composition or where

they were formed. (ESRT p.6)

• #5. Explain how igneous rock texture is related to

crystal size. (ESRT p.6)

3 Families of Rocks

• Igneous

• Sedimentary

• Metamorphic

Let’s start first with the mother of all rock families….

Igneous – Latin igneus, from ignis fire

“Of, relating to, or resembling fire.”

Source: Merriam-Webster

1. Igneous Rocks: Form from the solidification and/or

crystallization of liquid or molten rock

____________: The process of becoming a solid igneous rock.

____________: Cooling of magma or lava creates crystals.

Solidification

Crystallization

B1 Igneous Rocks

____________: Molten rock underground. Magma

Lava ____________: Molten rock above ground.

Mineral crystals may form resulting in the igneous rock having a

crystalline texture.

***Crystals within a rock are a good indicator of an igneous origin.

II. Igneous Rock Texture and Crystal Size

The texture of the igneous rocks (size of the crystals) is dependent

upon the rate of cooling.

If molten rock cools slowly the crystals will be LARGE.

_______ crystals mean ______ texture (_________). LARGE coarse Phaneritic

If molten rock cools rapidly the crystals will be small.

Small crystals mean fine texture (Aphanitic).

When molten rock is quenched (cooled extremely fast), no crystals

form and is said to have a glassy texture. Ex: obsidian

Vesicular rocks are created when gases remain trapped in

a quickly cooling rock. Air pockets, called vesicles, are

the visible evidence. Ex: Scoria

Graph showing relative rate of cooling

vs. crystal size of igneous rocks

Rate of Cooling

Slow Fast

Cry

stal

Siz

e

Large

Small

III. Environment of Formation: _____________________.

Intrusive: _______ rocks produce _____________________

crystals due to slow underground cooling from magma

Plutonic

Where the rock solidified

Large (1 mm and larger)

Extrusive: ________ rocks produce ___________________

crystals because lava cools faster near or on Earth’s surface

Volcanic Small (less than 1 mm)

Intrusive igneous rock:

Extrusive igneous rock:

Deep Underground

Near or on Earth’s Surface

IV. Composition: ___________________________________. The type of minerals that make up the rock

Rocks that are:

Mafic : ______________________________

______________.

Dark in color, high in density,

high in iron and magnesium

Felsic : ____________________________

_______________.

Light in color, low in density,

high in Aluminum

Exception: Obsidian is dark color but felsic composition.

Felsic Mafic

C. Density: _________________________________. Depends on the composition of the rock

High density _____ in color and _____ in composition. Dark Mafic

Low density _____ in color and _____ in composition. Light Felsic

Mafic Felsic

3. Classification of Igneous Rocks

Classification based on: A. Color: _______________________.

Exception: ________ Obsidian

The overall color of the rock

Light colored rocks are composed primarily

of: __________________. Quartz and feldspars

Dark colored rocks are composed primarily

of: __________________. Pyroxene and Olivine

Now let’s take a look at your ESRT’s

• V. Igneous rocks of different composition

may form from the same body of magma.

– some minerals, like quartz and mica melt and

solidify at low temperatures and take a long

time to solidify out of hot magma.

– Other minerals such as olivine and pyroxene

melt and solidify at higher temperatures. These

minerals settle out of magma quicker.

This is reason that igneous rocks containing olivine do not

usually contain quartz or mica.

Continental Crust vs. Oceanic Crust

• Composition

• Density

• Color

• Rock Type

Continental Crust Oceanic Crust

felsic mafic

low high

light dark

granite basalt

Sedimentary Rock Objectives

• #6. What is a sedimentary rock and what

are three good indicators of one?

(ESRT p.6)

• #7. Describe the three types of sedimentary

rock and how each is formed.

(ESRT p.7)

B2 Sedimentary Rocks Weathering breaks rock and produces sediments which are

transported by water, wind and glaciers. Sediments can form

sedimentary rocks in a number of ways.

Sedimentary rocks are usually found as a thin coating or

veneer on top of other rocks! (like dust on your window sill.)

Sedimentary rock often contain rounded particles cemented in

layers because running water is the major transporting agent.

Many of the rocks form under large bodies of water in 3 major

ways.

I. Clastic Sedimentary Rocks:

Microscopic

clay-sized

fragments

Formed from sediments by the processes of

compression (compaction) and cementation

Compression-

pressure of ocean

water and above

sediments

compact small

particles into

rock.

Very small compacted clay particles can form shale.

I. Clastic Sedimentary Rocks continued:

Cementation- sediments are

combined with mineral cements

that precipitate out of ground water

Precipitate means settle out of solution

Three common cements are

silica, iron and lime.

Common cemented clastic sedimentary rocks are

sandstone, breccia and conglomerate.

II. Chemical Sedimentary Rocks

(Crystalline, not clastic):

•Form from processes of evaporation and precipitation

•Evaporation- salt water evaporates (turns to gas) and

leaves solid minerals behind to form rock called

evaporites

•Precipitation- Solid minerals settle to bottom of salt

water solution forming rock called precipitates

•Evaporites and precipitates are monomineralic

meaning composed of only one mineral. Four common

evaporites and precipitates are rock salt, rock gypsum,

dolostone and limestone.

III. Biological or Organic

Sedimentary Rocks (Bioclastic)

• Rocks formed from the remains of plant or

animal materials

•Bituminous Coal

comes from

compacted plant

remains

•Fossil limestone

comes from

cemented shells and

animal remains

Sedimentary Rocks can be classified into 3 major groups:

Clastic

(Fragmental)

Bioclastic

(Organic)

Crystalline

(Chemical)

Underwater

(on the seafloor)

In the presence

of water In the presence

of water

Fragments of

broken rocks

Salts

(Monominerallic)

Origin

Composition

Method of

Lithification

(rock formation)

Compaction &

Cementation

Precipitation

and evaporation

from salty water

Compaction

of dead

material

Once-living

remains

Sedimentary Rocks are the official

rock of “Fossils”

***If you see a fossil, it’s in a sedimentary rock!

Presence of sediments

Layers in Rock

Three good indicators of Sedimentary Rocks are:

Presence of Fossils

Metamorphic Rock Objectives

• #8: How are metamorphic rocks formed and

what are some indicators that metamorphism

has taken place? (ESRT p6&7)

• #9. Explain the two types of metamorphism.

• Metamorphism usually takes place deep within the

Earth. This is where the very high temperatures,

high pressures and hot chemical solutions can be

found that cause recrystallization forming

metamorphic rock.

B3 Metamorphic Rocks

Larger

garnet

crystals in

schist grow

due to

intense heat

& pressure!

•Metamorphism results in recrystallization of unmelted

minerals under high temperatures and pressures.

•These extreme conditions cause the mineral crystals to

grow and new minerals to form without melting which

is the process called recrystallization.

The original rock from which metamorphic rocks are formed

is called the __________. Parent Rock

Parents Rock!

Not a

Metamorphic

rock

Parent rock may be igneous, sedimentary or metamorphic.

They look similar

but are different in

the following

ways…

Parent (Shale)

Metamorphic

“Version” (Slate)

Indicators of Metamorphism:

• Metamorphic rocks can be

hard, very dense and less

porous!

• Distorted structure:

Metamorphic rocks also show

bending & twisting due to

uneven pressure. Original

sedimentary rocks layers may

become bent or folded from

pressure as they change into

metamorphic rock.

•Garnet and/or mica crystals present helps to identify met. rocks

Metamorphic Rocks are classified into two groups.

1. Foliated: _____________________________________

_____________________________________

__________.

Alignment of minerals or the separation of

minerals into platy (flaky) layers of light and

dark bands

Foliation commonly appears as _______. Banding

Generally the more intense the temperature and

pressure, the thicker the mineral bands will be.

Thick banding indicates a high degree of

metamorphism.

Notice how your ESRT’s shows

banding?

2. Non Foliated: _____________________________

____________________________________.

Rocks that generally have uniform

Composition (little or no grain arrangement)

Non foliated rocks DO NOT have bands

Form as a result of equal pressure being applied in all

Directions OR contact with hot rock.

Pressure equal in

all directions

Ex: __________________ Quartzite and Marble

1. Contact (Thermal) Metamorphism

Occurs where: ___________________________________

___________.

Molten magma (lava) comes in contact with

other rocks

***The rocks are “cooked” but not melted.*** Contact metamorphism occurs over a small area.

Ex: ___________________________________________ Vein of magma (dike) or around a magma chamber Vein of magma is hot!!!

Contact Metamorphism

Two Types of Metamorphism:

Transition Zone -gradual change from original unaltered rock to altered metamorphic

Any rock can undergo contact metamorphism as long as the heat is strong enough.

2. Regional Metamorphism

Occurs at: ______________________________________

______________________________________.

Margins of continents where the rock is deeply

buried and exposed to extremely high pressures

Ex: ________________________________________ Continental Collision and Bottom of Lithosphere

Regional metamorphism

occurs here over a large area

Regional

metamorphism

is associated

with orogeny

or mountain

building

processes.

Name Metamorphic Rock produced

from each Parent Rock • Shale Slate

• Sandstone Quartzite

• Limestone Marble

• Dolostone Marble

• Conglomerate Metaconglomerate

• Granite Gneiss

Different metamorphic rocks may be formed from the

same parent rock depending upon the pressure and

temperature in the environment in which it forms.

Ex: ________________________ Gneiss, Schist, and Phyllite

Different metamorphic rocks can be formed from the same parent

rock depending on the degree of Metamorphism in which it formed.

For example:

Shale + H/P Slate + H/P Phyllite + H/P Schist + H/P Gneiss

Depends on Degree of

Metamorphism

VI. Distribution of Rock Types

a) Covers continent as thin layer or veneer? • Sedimentary

b) Found at or near surface of volcanoes and mountains?

• Igneous

c) How are intrusive igneous and metamorphic rocks found at Earth’s surface instead of deep below?

• Forces have pushed these rocks upward towards the surface

Rock Cycle Objective

• #10. Be able to interpret the Rock Cycle

diagram on page 6 of the ESRT.

Row, Row, Row Your Rocks

• Sedimentary rocks, mostly found in layers

• Often found near water sources with fossils from

decayers

• Then there's igneous rock here since earth was

born

• Molten lava crystallized and that's how they form

• Metamorphic rocks come from rocks that change

• Pressure, heat, and chemicals atoms rearrange

• Rocks changing back and forth a never ending

story

• So many things to know rocks are never boring

C The Rock Cycle The Rock Cycle is: ______________________________________

________________________. A model to show all possible changes that

rocks can go through.

The amount of rock material on Earth remains constant , with

the exception of ___________________

___________________.

Extraterrestrial material

from space (Meteorite)

Any type of rock, Igneous, Sedimentary, or Metamorphic,

may be changed into any other type depending upon the

environment to which it is subjected.

There is no preferred or predictable path that a rock will take

within the environment.

ESRT Page 6

1. List 3 processes needed for an igneous rock to become sedimentary.

2. What must happen to a sedimentary rock to make it metamorphic?

3. What’s one word that all rocks are called before they become igneous rock?

Rock/Mineral Resource Objectives

• #11. What are fossil fuels and how do they

impact our society?

• #12. Why is the conservation of minerals

and resources important?

D. Environment of Rock Formation & Use depend on composition, structure and texture

• Granite-

– takes polishing, used for monuments & buildings

• Gabbro-

– large dark crystals, used for road base

• Sandstone-

– layers, used for building, “blocks”

• Slate-

– easy to cut, used for roofing tiles, flagstone, & pool tables

• Marble-

– nonfoliated, used for statues & ornaments

Useful properties of Rocks & Minerals include:

•Stone for building materials:

•Roads

•Buildings

•Making concrete

Land Use and Rocks • What humans can do in a given geographic

area often depends on the local bedrock.

– Limestone rock for farming

– Granite & gneisses make great bedrock for

skyscrapers! (think NYC)

– Some igneous/metamorphic bedrock forms

thins soil and is almost impossible to grow food

on. (think Adirondacks Mts.)

E. Resource Conservation

• With the Earth’s population rapidly increasing,

the demand for energy and resources is rapidly

increasing as well.

• Direct Relationship

Earth’s Population

Dem

an

d f

or

En

ergy

& R

esou

rces

At the present time, fossil fuels are primary source of ______. energy

Fossil fuels and most minerals are ____________________

because _____________________________________.

Nonrenewable resources

they are being used faster than they can form

Fossil fuels- Hydrocarbon deposit in Earth formed from

organic matter in the past such as coal, oil, and

natural gas.

Fossil Fuels: • Coal, oil and natural gas

provide most of the worlds

energy.

• These “fossil fuels” are

nonrenewable in our

lifetimes.

• Means we are using them

faster than they can be

made/replaced

• What will we do when

they become too scarce to

obtain???

Fossil Fuels

• Beside being used for energy, also used to

make plastics, medicines, cosmetics,

fabrics, etc.

• With such a demand on fossil fuels, some countries have become wealthy due their fossil fuel reserves.

• Uneven distribution of resources and increasing demand for dwindling resources results in higher prices which alters many peoples standard of living (either for the better or the worse) and in the past has even resulted in wars.

Minerals and Humans:

Humans have designed an entire economy around minerals! Without them, our lives would look completely different! Imagine:

• No electronics (cell phones, TV, video)

• No gemstones

• No pencil graphite or lead

• No cosmetics (sorry girls)

• No automobiles, bicycles, etc…..

• The list could go on and on….

•Metals for:

•Electronics

•Building materials (structural steel)

•Investment (gold, silver, platinum)

•Minerals for:

•Just about everything not plastic!

•Gemstones (jewelry & investment)

Global Distribution: • Minerals can only be mined wherever they are

found! Often, mineral resources are found only in

remote, hard-to-reach places.

How can we reduce the current usage rate of our natural resources?

1. _____________________________________________________

2. _____________________________________________________

_______________________________________

3. _____________________________________________________

Finding and using alternative energy sources (Solar, Hydropower,

Wind, Geothermal, and Nuclear Energy)

Practice the 4 R’s (Reduce, Reuse, Recycle, Reclaim)

Replace inefficient technology with superior technology