Minerals• Naturally occurring uniform (homogeneous)

substances that are inorganic. (Not formed by or from living things.)

• Minerals have definite physical and chemical properties.

• Only a few minerals are found everywhere making up most of the rocks on Earth. – Quartz, Feldspar, Calcite, Mica, Magnetite

• Oxygen and Silicon make up for most of the mass of these minerals.

Rocks• Most rocks are composed of one

or more minerals–One mineral = monominerallic–Two or more = polyminerallic

• Geologists classify rocks based upon their origin

Rock Types

1.Sedimentary

2.Igneous

3.Metamorphic

Sedimentary Rocks• Most are composed primarily of the

weathered remains of other rocks.• Usually formed by compression and

cementation of sediments.• Grains are usually rounded by

abrasion and deposited in layers.• Relatively thin layer at the earth’s

surface.

Igneous Rocks• Form by the crystallization of molten magma

or lava.• From the crystal size we can infer the rate of

cooling– Very Fast cooling can produce a glass (no visible

crystals)– Slow cooling allows visible crystals to form– Crystal size often varies with depth of formation

• Deep – slow cooling with large crystals

Metamorphic Rocks• Form when sedimentary, igneous or

metamorphic rocks are changed by heat and/or pressure.

• Recrystallization without melting.• Change deep within the earth.• Metamorphic rocks often show foliation

(mineral alignment – Ex. schist) or banding (separation of minerals – Ex. Gneiss) and high in density.