Igneous Rocks From 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 Rocks Formed 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 Rocks Changed 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…) hwDlntw 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