rocks & minerals

Unit 2Unit 2

•Rocks and MineralsLithosphereLithosphere

OK – so here’s the real introduction to OK – so here’s the real introduction to Rocks & MineralsRocks & Minerals

What is a Mineral?What is a Mineral?

• Solid Earth Materials

• Naturally Occurring

• Inorganic

• Definite Chemical Formula

• Definite Crystal Structure

Minerals Minerals

ESRT Pg 16

Minerals can beidentified bytheir chemicaland physicalproperties.

What is a

Mineral?

Minerals Fist List

High Five!!

Solid, Earth Material

What does that mean?!?!?!

--Not a gas or a liquid

--Has a definite shape and volume

QUESTION?Is oil a mineral??

Answer…No, because it is a liquid.

Naturally O

ccurringWhat does that mean?!?!?!

--Not man-made

Inor

gani

c

What does that mean?!?!?!

--Not formed from living things or the remains of living things

--NON-LIVING!!

EXAMPLES

1. Coal is NOT a mineral because it comes from plants.2. Amber is NOT a mineral because it comes from tree sap.3. A pearl is NOT a mineral because it comes from oysters.

Def

inite

Che

mic

al F

orm

ula

What does that mean?!?!?!

--The elements that make up the minerals are combinedin definite proportions

--Chemical formula can be found on page 16 ofESRT.

EXAMPLES-Gold (Au)-Pyrite (FeS²)-Graphite (C)-Diamond (C)

Definite

Crys

tal Stru

cture

What does that mean?!?!?!

--Atoms are arranged in a repeating pattern

--Each mineral has a different INTERNAL ARRANGEMENT OF ATOMS that gives it distinct physical and chemical properties

What does that What does that mean?!?!?!mean?!?!?!

Defini

te C

rysta

l Stru

cture

QUESTION

How does the mineral graphite,which is soft have the same chemical formula as diamond,which is the hardest mineralin the world?

ANSWER

Because their internalarrangement of atoms are different

How are Minerals

Identified??

Fill in the spiders legs as we go!!

ESRT Pg 16

Minerals can beidentified bytheir chemicaland physicalproperties.

Color

How are Minerals Identified??

--Least useful for identification

--One mineral can come in many colors

EXAMPLE: --Hematite: Comes in black, red and brown

How are Minerals Identified??

1. Some minerals are always the same color

2. Some minerals can have many colors

Smoky QuartzRose Quartz Quartz

Sulfur

Colors can vary as a result of…Colors can vary as a result of…

A. Chemical Impurities– Cobalt compounds tend to be pink, purple, or blue

Manganese—tends to produce pink colors

Colors can vary as a result of…Colors can vary as a result of…

B. Oxidation—exposure to air and water changing the color of the mineral.

Ex. Rust

--Iron is the dominant coloring agent in rocks and soils

How are Minerals Identified??

Streak

--the color of a mineral when it is finely powdered

--determined by rubbing the mineral on a piece of tile

Hematite has a reddish-brown streak.

How are Minerals Identified??

Luster

--describes how a mineral appears to reflect light

There are 2 categories in which a minerals luster can fall…

Metallic OR Non-Metallic

How are Minerals Identified??How are Minerals Identified??

A. Metallic– reflects light like metal (shiny)

GalenaGraphite

Pyrite

How are Minerals Identified??How are Minerals Identified??

B. Non-Metallic—any mineral which DOES NOT exhibit shiny metallic characteristics

Ex. Quartz

Metallic or Non-Metallic??Metallic or Non-Metallic??

Non-Metallic

Mica

Pearly luster

Metallic

Magnetite

Metallic or Non-Metallic??Metallic or Non-Metallic??

Non-Metallic

Pyroxene

Dull luster

How are Minerals Identified??

Hardness

--Resistance of a mineral to being scratched

--Moh’s Hardness Scale—compares the hardness of the mineral to 10 reference minerals.

How is Hardness Determined??How is Hardness Determined??

Softest

Hardest

The scale consists of number 1 through 10; 1 being the softest and 10 being the hardest. Each number represents a different mineral- each harder than the previous. The 10 minerals are to the left.

How is Hardness Determined??How is Hardness Determined??

Several common household items have a fixed hardness, and can be used to test for hardness.

-Fingernail = 2.5-Copper penny = 3-3.5-Nail = 4.5-Knife blade = 5.5-Glass = 5.5-Steel file = 6.5-Streak plate = 7

What Determines Hardness?What Determines Hardness?

--Hardness is determined by a minerals internal arrangement of atoms.

Ex. Diamond vs. Graphite-Diamond has hardness of 10 and graphite is ranked between 1 and 2. Diamond is about 40 times harder than graphite due to the way the atoms are arranged.

--Hardness is the best property to use to identify a mineral.

How are Minerals Identified??

Cleavage or

Fracture

Cleavage—when a mineral breaks along a flat, smooth surface

Examples of Minerals that show CleavageExamples of Minerals that show Cleavage

Mica exhibits basal cleavage.

Galena exhibits cubic cleavage.

What Determines Cleavage?What Determines Cleavage?

A minerals internal arrangement of atoms!!

How are Minerals Identified??How are Minerals Identified??

Cleavage or

Fracture

Fracture—When a mineral breaks along irregular rough surfaces.

EX. Quartz

How are Minerals Identified??

Density or Heft

--The amount of matter in a given space (mass/volume)

Depends on…

-kind of atoms which make up the mineral

-how the atoms are arranged in the crystal lattice

How are Minerals Identified??

Crystal Shape

--Minerals have a characteristic crystal shape resulting from the atomic packing of the atoms when the mineral is forming

How are Minerals Identified??

Special Properties

-Magnetism (Magnetite)

-Glowing under ultraviolet light (Fluorite)

-Salty taste (Halite)

-Smell (Sulfur)

-Reaction to HCl (Calcite)

IMPORTANT!IMPORTANT!

• Remember on the Regent’s Exam most of the information about the mineral in a question will be given to you or you will observe from the diagrams on the Exam. Use them to your advantage. Make sure you know the basics about mineral identification and observe carefully…….

• USE PAGE 16 OF THE ESRT

How are rocks How are rocks formed?formed?

Rocks are classified Rocks are classified by their process of by their process of

formation.formation.

LithosphereLithosphere

Igneous

Sedimentary

Metamorphic

sedimentssediments and mineralsminerals are compacted

and cemented With dissolved minerals

ClasticClastic – pieces of other rocksCemented into

rock

ChemicalChemical – Evaporites

From seawater

Organic/Bioclastic Organic/Bioclastic Remains of plantsOr animals whichAre transformed

Into rock

ROCKSROCKS

Sedimentary RocksSedimentary RocksForm whenForm when

Minerals

Clastic

And

Are cemented together

The 3 types of sedimentary rock are

SEDIMENTS

Chemical Organic

pg 6 in your notes

Texture and Grain SizeTexture and Grain Size

• Texture is described based on grain size, grain shape, and grain pattern.

• Most rocks are made up of tiny particles of minerals or other rocks, which are called grains.

• A rock’s grains give it its texture

•Through the process of

, rock is loosened and carried away with wind and water by

. The sediment then settles out of the wind and water during depositiondeposition. The sediment begins to settle out and form

.

Origins of Sedimentary RockOrigins of Sedimentary Rock – Draw an arrow from “CLASTIC”

weatheringweathering

erosionerosion

layerslayers

compactioncompaction

CementationCementation

As the layers stack up, they become heavier until the weight squeezes the layers together during

.

Dissolved minerals act as glue in a process known as .

Earth Science Reference Table Page 7Earth Science Reference Table Page 7

• This is a sample of breccia, a coarse-grained sedimentary rock with coarse, angular fragments.

• This is a sample of sandstone, a sedimentary rock that formed from sand grains.

ChemicalChemical

• Formed when minerals dissolved in water, precipitate out and form crystals on the sea floor – Includes evaporites.

Earth Science Reference Table Page 7Earth Science Reference Table Page 7

Organic (bioclastic) – rocks formed from the remains of plants and/or animals that undergoes a transformation into rock.

• This is a sample of limestone, a sedimentary rock made of calcium carbonate that formed under water indirectly from the remains of tiny marine organisms.

Coal FormationCoal Formation

Grand CanyonGrand Canyon

Rocks classified on the basis of their

formation (how they are made)

Monomineralic Polymineralic

Composed of 1 mineral

EX:

Limestone - Calcite

Composed of many minerals

Ex: Granite

Feldspar, quartz, hornblende

Igneous RockIgneous Rock• Igneous rock forms

when magma or lava

COOLSCOOLS SolidifiesSolidifiesCrystallizesCrystallizes

hardenshardens

CrystallizationCrystallization

TEXTURE

Intrusiveor Plutonic

Extrusive or Volcanic

Coarse Grained large crystalsNon-Vesicular

(no gas bubbles)

Magma

UndergroundSlow cooling

Fine Grained (small crystals)Glassy

Gas Pockets (vesicular)

LAVA

Above groundFAST cooling

Granite vs. ObsidianGranite vs. Obsidian

Extrusive

Intrusive

Igneous RockIgneous Rock

Mineral Composition

FELSICFELSICLow density

MAFICMAFICHigh Density

Rich in AluminumRich in Aluminum Rich in IRON &Rich in IRON &MagnesiumMagnesium

Light Colored

Rocks Called

Dark Colored

Rocks Called

Igneous Rock chart found on Igneous Rock chart found on page 6page 6 of of Reference Tables Reference Tables

High light it in your ESRT!High light it in your ESRT!

Rock characteristics can be determined using this chart

Mineral content can also be determined using this chart

Ho

w to

read it!

Ho

w to

read it!

Metamorphic RocksMetamorphic Rocks

ConditionsConditions that cause rocks to that cause rocks to

undergo metamorphism undergo metamorphism includeinclude::

• Deep burial and pressure or hot contact zones

• Metamorphic rocks are often found in mountainous regions

You’ll have to add this to your notes on page 8

Heat

Pressure

Chemical due to Contact

Metamorphic rocks are characterized by:

• Increased DENSITY

• NEW Minerals

• BANDING

Metamorphic Rocks – Metamorphic Rocks – formed when a rock formed when a rock

is changed byis changed by

Metamorphic Rocks are classified by the arrangement of their:

MINERALSMINERALS

Into two types of metamorphic Into two types of metamorphic rocks called:rocks called:

Non - Foliated

Foliated and

Bottom of Page 7 of ESRT Bottom of Page 7 of ESRT

Where the minerals grains areWhere the minerals grains are

Not aligned and appear MASSIVE

Squeezed and curved or

folded

Foliated (think Foliated (think FOLD)FOLD)

Mica SchistMica Schist

GneissGneiss

Increased HEAT Increased HEAT and PRESSUREand PRESSURE

Non-FoliatedNon-Foliated

• Massive Massive Metamorphic Metamorphic rocksrocks

Metamorphic Rock Chart Metamorphic Rock Chart (page 7 Earth Science (page 7 Earth Science Reference TableReference Table

• Increasing metamorphic change occurs with increasing temperatures and pressures.

• If the melting point is reached, the change is no longer metamorphic, and igneous rocks are formed.

The Rock CycleThe Rock Cycle(Page 6 of Earth Science Reference Table)(Page 6 of Earth Science Reference Table)

• The Rock Cycle describes the continually changing structure of rocks.

Distribution of Rocks in the U.S.Distribution of Rocks in the U.S.