Rocks & Minerals

Minerals

Saddle-shaped pink dolomite crystals.

What is a Mineral? Naturally Occurring Inorganic Solid Definite Chemical Formula Definite Crystal Structure

Galena

Beryl

Naturally Occurring Formed by natural processes not in

the laboratory. - Is an Ice Cube a mineral? - Is the ice on the wind-

shield of a car a mineral? - What about the ice in

your refrigerator?

Inorganic Formed by inorganic processes; not

living Does not contain chains of carbon

atoms

Solid Not gas or liquid

H2O as ice in a glacier or a snowflake is a mineral, but liquid water in the ocean is not.

The element mercury is a metal that’s a liquid at room temperature/pressure. Liquid mercury is NOT a mineral!

Definite Crystal Structure Highly ordered atomic arrangement

of atoms in regular geometric patterns

8 Tourmaline

K-spar FluoritePyrite

KyaniteFluorite

Crystal Structure of Ice

Definite Chemical Formula Minerals are expressed by a specific

chemical formula-Gold (Au)-Calcite (CaCO3)

-Quartz (SiO2)-Pyrite (FeS2)

Composition of the Earth’s Crust

Eight Elements that make up over 98% of Earth’s Crust-Oxygen (O)-Silicon (SI)-Aluminum (Al)-Iron (Fe)-Calcium (Ca)-Sodium (Na)-Potassium (K)-Magnesium (Mg)

Where Do Minerals Come From?Crystallize from magma and

lava.

Precipitate from water due to evaporation.Olive crystallizes

from mafic magma.

How Are Minerals Identified? Color Luster Hardness Streak Density Crystal Shape Cleavage and Fracture Special Properties

Color Usually the first and most easily

observed-Some minerals are always the same color-Some minerals can have many colors

QUARTZROSE QUARTZ SMOKY QUARTZ

Luster General appearance of a mineral

surface in reflected light

Glassy-Obsidian

Hardness Resistance to scratching by

different items; “scratchability”

Mohs Hardness Scale>2 fingernail 3 penny ~5 Steel of a pocket knife 5.5 Window Glass6.6 Steel of a file 7 quartz crystal

Mohs Mineral Hardness Scale

1) Talc 2) Gypsum 3) Calcite 4) Flourite 5) Apatite 6) Feldspar 7) Quartz 8) Topaz 9)

Corundum 10) Diamond

Softest

Hardest

1

2

3

4

5

6

7

8

9

10

Streak The color of a finely powdered mineral Determined by rubbing the mineral on a

piece of unglazed porcelain (streak plate)

Density The amount of matter in a given

space (Mass/Volume)

Crystal Shape Minerals have a characteristic crystal

shape resulting from the atomic packing of the atoms when the mineral is forming

Cleavage and Fracture Cleavage is the tendency of a

mineral to split or crack along parallel or flat planes

Rhombohedral cleavage forms “smushed” cubes

(calcite).

Octahedral Cleavage forms bi-pyramids (Fluorite)

One direction of cleavage = basal

cleavage (biotite mica).

Cleavage and Fracture Fracture occurs when a mineral

breaks at random lines instead of at consistent cleavage planes.

Conchoidal fracture is what gives quartz, obsidian, chert, and flint those super-sharp edges!

Quartz has no cleavage and instead exhibits conchoidal fracture.

Special Properties Magnetism (Magnetite) Optical Properties (calcite and

ulexite) Glowing under ultraviolet light

(Fluorite) Salty taste (Halite) Smell (Sulfur) Reaction to weak acids (Calcite)

Magnetite

Economic Importance of Minerals

Minerals are in many things we see and use everyday such as; bricks, glass, cement, plaster, iron, gold

Every American Requires 40,000 Pounds of New Minerals

per Year at this level of consumption the average newborn

infant will need a lifetime supply of:-795 lbs of lead (car batteries, electric components)-757 lbs of zinc (to make brass, rubber, paints)-1500lbs of copper (electrical motors, wirings-3593 lbs aluminum (soda cans, aircraft)-32,700 lbs of iron (kitchen utensils, automobiles, buildings)-28,213 lbs of salt (cooking, detergents)-1,238,101 lbs of stone, sand, gravel, cement (roads, homes, etc.)

Rocks

Rocks Made of two or more different

minerals that have been: cemented togethersqueezed and heated together melted and cooled together.

Types of Rocks Igneous Sedimentary Metamorphic

Igneous Rocks Most igneous rocks are produced

deep underground by the cooling and hardening of magma

Sedimentary Rocks Formed from the breaking apart of

other rocks (igneous, metamorphic, or sedimentary rocks) and the cementation, compaction and recrystallization of these broken pieces of rock

Fact about the Mississippi River

Did You Know?

The Mississippi River carries an average of 436,000 tons of sediment each day

It moves an average of 159,000,000 tons of sediment a year

Metamorphic Rocks Formed from heat and pressure

changing the original or parent rock into a completely new rock. The parent rock can be either sedimentary, igneous, or even another metamorphic rock.

The Rock Cycle The diagram of the rock cycle shows how

the earth's rocks are changed again and again

Classification of Igneous Rocks

Composition-refers to the minerals that make up the rock

Texture-shape, size, arrangement and distribution of minerals that make up the rock

Composition Extrusive- Formed from lava; volcanic

Intrusive- Formed deep within the earth

Obsidian Pumice

Granite

Textures Glassy

Fine-grained

Coarse-grained

PorphyriticObsidian Granite

Granite

Basalt

Classification of Sedimentary Rocks

Clastic Rocks- Made of the fragments of previously existing rocks

Organic Rocks- Come from organisms

Chemical Rocks- Formed by inorganic processes such as evaporation

Clastics Rocks Conglomerate

Sandstone

Mudstone

Organic Rocks Limestone

Coquina Fossiliferous Limestone

Chemical Rocks Limestone

Metamorphic Rocks Foliated- Parallel alignment of flattened

mineral grains and pebbles Unfoliated-Rocks that are not

banded and do not break into layers

Foliated

Gneisse

Unfoliated

Marble

Distribution of Rocks in the U.S.