MINERALS AND ROCKS

THE TREASURES OF OUR EARTH!

REVIEW THIS POWERPOINT OFTEN—IT IS EVERYTHING

YOU NEED TO KNOW!

MINERAL:A. Naturally occurring

B. Inorganic, Solid

C. Crystalline structure

D. Definite chemical and

physical properties

E. Definite molecular structure

(internal arrangement of atoms)

Minerals are identified based on their physical properties 1. Color

• Most visible property, but least reliable.

• Many minerals have the same color and some have more than one color.

2. Streak• Color of a mineral in its powder form

3. Luster• The way in which light is

reflected from the surface

a. Metallic - shines like polished metals, rust, heavy

b. Nonmetallic - no metallic luster

1) glassy, clear

2) pearly, white

3) greasy

4) dull

5) earthy

nonmetallic

metallic

4. Hardness

a. the resistance of a mineral is compared to glass by scratching it against a glass plate (5.5)

b. hardness of a mineral is determined by Moh's Scale of Hardness (1 – 10)

5. Cleavage

The tendency of a mineral to split along flat, even surfaces.

Fracture -Uneven breakage of a mineral.

(minerals that do not have cleavage have this!)

Other Properties:a. Magnetic

b. React with dilute

hydrochloric acid by

effervescing bubbles

c. Taste (salty)

d. Fluorescence

e. Double refraction

f. Radioactive

Minerals Relationship to Rocks:

• Minerals form rocks.

• Most rocks are composed of one or more minerals

• Monominerallic - composed of one mineral

• Polyminerallic - composed of more than one mineral

• 10 - 15 minerals form most all of the rocks on Earth, they are called rock-forming minerals.

Silicates minerals (SiO4)– two

minerals combine to form a compound.

• When they combine they create a structure called the Silicon-Oxygen Tetrahedron

3 Rock Types:Igneous Sedimentary Metamorphic

Rocks are classified based on their: Rocks are classified based on their: OriginOriginIn other words, what environment did they form in??? In other words, what environment did they form in???

CrystalsSediments

Recrystallizedcrystals

Igneous Rocks

Formed by cooling and solidification of

lava or magma.

Lava: extrusive

Magma: intrusive

C ourseG ra ined

FineG ra ined

G lassy

Fe lsic(L igh t co lored)

C ourseG ra ined

FineG ra ined

G lassy

M afic(D ark co lored)

Igneous rocks

A. Igneous RocksIgneous Rocks Intrusive- cools and solidifies from magma

(beneath Earth’s surface), making larger crystals due to slow cooling.

Granite (coarse crystal texture)

Extrusive – cools and solidifies from lava (at or near Earth’s surface), making smaller crystals due to faster cooling.

Obsidian (glassy texture) Pumice (glassy texture with vesicles)

Igneous Rock Characteristics

Felsic- forms light-colored rocks that are high in Al, low density.

Mafic- forms dark-colored rocks that are high in Mg and Fe, high density.

Vesicular- gas bubbles or air pockets.

Cooling Time Graph(the longer it takes to cool, the bigger the crystals!)

As time increases, crystal size increases.

IGNEOUS ROCKS

Crystal sizeDescription

Grain Size

Igneous rocks have “Intergrown Crystals” – crystals

that form as the rock forms.

IntergrownCrystals

Not IntergrownCrystals

Where the rock formed

Outside the volcano: Extrusive (lava)

Inside the Earth: Intrusive (magma)

Air Bubbles in the rock?Yes= Vesicular

No Air Bubbles? No = Non-vesicular

ColorLight Dark

Ligh

test

Darke

st

DensityLow Density High Density

What Minerals Are in the Rocks?First, identify the rock, then go straight down the column for the minerals.

This is the amount of Potassium Feldspar in the rock.

This is the amount of Quartz in the rock.

This is the amount of Plagioclase Feldspar in the rock.

Use tick marks on a scrap paper to measure the percentage.Potassium Feldspar 25%

Quartz 40%

PracticeName a light-colored, fine-grainedrock with no bubbles.

Name a coarse-grained, dense rock.

Name a very light-colored, glassy, extrusive rock with bubbles.

Metamorphic Rocks

• Form from metamorphism (change) that is caused by heat and pressure.

• Usually form deep in the Earth's crust

• Causes a change in the rocks 1. makes the rock more dense2. separates the rock into layers (banding)

• Metamorphic rocks have been changed from a pre-existing rock.

• Caused by extreme heat and/or pressure. (regional)

• Happens over wide “regions.”• Caused by contact with extreme heat

from a nearby volcano (contact).• Occurs when the rock is in close

contact with volcanic heat.

Types of Metamorphic Rocks:

1. Contact Metamorphic - Rocks that form from being close to a heat source (magma)

2. Regional Metamorphic

a. caused mainly by pressure

b. usually cover large areas

c. form during tectonic activity

d. most metamorphic rocks are

formed from regional metamorphism

Metamorphism happens where lava or magma touches other rocks. What will this limestone rock metamorphose into?

Classification of Metamorphic Rocks

Non-foliated - no visible layers (distorted crystals)

Marble

Foliated Metamorphic Rock – mineral alignment

a. visible layers in the rock

b. form from extreme pressure which flattens the minerals into layers

c. different mineral densities may produce alternating light and dark bands of minerals (banding)

A “GNEISS” ROCK

Sedimentary Rocks:Rocks formed from sediments on Earth’s surface.

Sedimentary Rocks form from sediments that go through cementation & compaction

EXAMPLES OF SEDIMENT SIZE FROM LARGEST TO

SMALLEST

Three main types

1. Clastic - made from other existing rock fragments. Clastic rocks are identified by the size of the fragments.

2. Chemical - form from minerals once dissolved in water.3. Organic - formed from once living organisms.

Features of Sedimentary Rocks:Stratification - layering of rocks caused by

different types of sediments being deposited

Fossils – only found in Sedimentary Rocks. These are the imprints left by a once-living organism.

1. Made from sediments or rock material that has been broken down in some way.

2. Sedimentary rocks are usually formed under water.

3. Often layered.4. Are the only rocks that contain

fossils!

Key Features of Sedimentary Rock

5.Clastic (fragmental) –made by compaction and cementation of sediments.

• See Earth Science References Tables

Mixed

Conglomerate Rock has rounded fragments

Rocks become rounded when they are exposed to water over longperiods of time, such as rocks formed at the bottom of a river bed.

Breccia Rock has angular fragments

Chemically formed rocks: Evaporites

1. Formed when water carrying minerals evaporates and leaves the minerals behind.

2. Are identified by the minerals present (such as halite forms Rock Salt)

• See Earth Science Reference Tables

• Bioclastic- •bio= life •clastic= fragments

• Made from accumulated shells (limestone) or plants (coal)

• See Earth Science Reference Tables

Formation of Coal

The Rock Cycle

Any rock can change into another type of rock!

EARTH SCIENCE REFERENCE TABLES CHART – PAGE 6

Earth Science Rocks!!! FOR YOUR TEST:

*Know the rock & minerals vocab

*Know the ESRT charts

*Practice Castle Learning

questions!