Igneous RocksFrom lava or magma

Can be either extrusive (formed on Earth’s surface, from lava)Or intrusive (formed inside of the Earth’s surface, from magma)

1. Granite•Intrusive (inside the Earth)•Light colored•High quartz content

2. Gabbro•Intrusive (inside the Earth)•Dark colored•Lower silica content

3. Rhyolite•Extrusive•Light colored (pinkish)•High quartz content

4. Basalt•Extrusive•Dark colored•Lower silica

5. Felsite•Extrusive•Light colored (light gray or whitish)•High in quartz

6. Pumice•Extrusive•“Fluffy” rock•Will float in water (until it gets water-logged)

7. Obsidian•Extrusive•Volcanic glass•Was used for arrowheads

Sedimentary RocksFormed from sediment

Can be either clastic (from little pieces)Chemical (settled from water)

Or Organic/Biochemical (from living things)

1. Conglomerate•Clastic•Contains larger rounded clasts (parts)

2. Sandstone•Clastic•Contains sand-sized grains

3. Shale•Clastic – although it doesn’t look like it•Made from mud or silt

4. Rock Salt•Chemical•Forms from the evaporation of water from salty oceans or lakes

5. Chert (or flint)•Chemical•Forms from the growth of silicon dioxide crystals

6 & 7. Limestone• Chemical or Biochemical• Formed from precipitation of calcium carbonate from water

(chemical)• OR from the accumulation of shells, corals, and alga material

8. Coal•Biochemical•Formed from the accumulation of plant material, usually in a swampy environment

Metamorphic RocksChanged Rocks

Can be either foliated or non-foliated

1. Marble•Non-foliated (not stripe-y)•Made from limestone (calcium carbonate)

2. Quartzite• Non-foliated•Made from sandstone (mostly quartz)

3. Amphibolite•Non-foliated•Made of amphibole and plagioclase, very little quartz

4. Slate•Foliated (has “layers”…like an onion…) http://www.youtube.com/watch?v=x2m_hwDlntw•Made from shale

5. Phyllite•Foliated•Made of fine grained mica•Usually lustrous

6. Gneiss•Foliated•Has lots of quartz and feldspar

7. Schist•Foliated•Contains mica, which allows it to split often