1. Rocks 1.Naturally occurring. Same as minerals. 2.Not living. Can be organic (just not alive now). Ex. coal 3.Solid mass of earth. No uniform crystal structure. Generally made up of several minerals.

2. 3 Types of Rock 1.Igneous = formed by melting and cooling rock. 2.Sedimentary = formed either by compaction and cementation of sediments, or evaporation of dissolved minerals (salt). 3.Metamorphic = already existing rock changed by heat, pressure, or chemical action.

3. Igneous Rocks Igneous means “fire” (Latin). Formed when molten rock (magma or lava) solidifies (solidification). Identified by: 1. Texture = crystal size 2. Composition = light or dark color.

4. Texture Extrusive (volcanic) = small crystals -- cools quickly above ground. Intrusive (plutonic) = large crystals -- cools slowly underground.

5. Composition Mafic = mostly heavy elements: Mg and Fe. - Dark color and dense (oceanic crust). Felsic = mostly light elements: Si, O, Al and K. - Light color and less dense (continents).

6. Identification 1.Texture = coarse, large crystals (intrusive) 2.Composition = light color (felsic)

7. Identification 1. Texture = fine, small crystals (extrusive). 2. Composition = dark color (mafic)

8. Identification Texture = small crystals (extrusive), vesicles. Vesicles = small holes or pockets. Composition = dark color (mafic)

9. Identification Texture = no crystals, glassy (extrusive). Composition = dark? No… actually clear when thinly cut (felsic).