Minerals

1. 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.

2. Rocks • Most rocks are composed of one or more minerals • One mineral = monominerallic • Two or more = polyminerallic • Geologists classify rocks based upon their origin

3. Rock Types • Sedimentary • Igneous • Metamorphic

4. 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.

5. 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

6. Metamorphic Rocks • Form when sedimentary, igneous or metamorphic rocks are changed by heat and/or pressure. • Recrystallizationwithout 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.