1. Rock Classification

2. 3 types of Rocks 1.Igneous Intrusive - granite Extrusive - basalt 2.Sedimentary Clastic - conglomerate Chemical – rock salt Organic - coal 3. Metamorphic Foliated - gneiss Non-foliated - marble

3. Origins Igneous –Extrusive: lava outside the crust; rapid cooling; fine grains –Intrusive: magma within the crust; slower cooling; coarse grains

4. Origins continued... Sedimentary - Clastic: rock fragments/particles; deposited – compacted – cemented to form rocks - Organic: once living organisms are deposited – pressed – compacted to form rock (peat to coal for example) - Chemical: dissolved minerals evaporation – crystallization forms rocks (halite; some limestone)

5. Origins continued... Metamorphic Heat, pressure and/or chemical reactions for 2 basic groups: - Foliated: banded and/or layers; may be split along those layers/bands (shale changes to slate) - Non-foliated: no visible banding (limestone changes to marble

6. Classifying Rocks 3 Basic Characteristics –Texture –Mineral Composition –Origin

7. Classifying Rocks continued... Texture –Grain size –Grain shape –Grain pattern –No visible graining

8. Classifying Rocks continued... Mineral composition –Check crystal structure using a sample and microscope –Check for magnetic properties –Acid test –Hardness

9. Classifying Rocks continued.. Origin –Igneous – from molten material (magma or lava) –Sedimentary – from deposited particles or other rocks, dissolved materials or deposited organic material Steps of sedimentation: erosion (produces the sediment) to deposition to compaction to cementation –Metamorphic – rocks that are changed due to heat/pressure and/or chemical reactions.