Types of Rocks

Igneous Rocks
- Textures:
• Glassy- no crystals; obsidian
• Fine-grained- interlocking; basalt
• Coarse-grained- same size; granite
• Porphyritic- large and small; trachyte
- Extrusive- formed from lava, some have air bubbles; obsidian, basalt, and pumice
- Intrusive- formed deep in Earth; granite, pegmatite

Sedimentary Rocks
Clastic- made up of other rocks, cemented together, conglomerate- one-third made of pebbles, sandstone- sand-sized grains
Organic- come from organisms, plants and shells, limestone- cemented shells together, coal
Chemical- inorganic processes, limestone- evaporated mineral water

Metamorphic Rocks
- changed by heat, great pressure and chemical reactions, different textures and structures, chemical reactions, can be formed from many kinds of rocks
- classification- based on arrangement of the grains that make up the rocks
• mineral crystals- parallel layers or bands
foliated- layers; schist, slate, and gneiss, nonfoliated- marble, quartzite

Minerals
mineral- naturally occuring, inorganic solid that has a definite chemical composition and crystal structure Identifying Minerals:
• Color
• Luster- metallic, non-metallic
• Hardness- Moh's Scale
• Streak
• Density- d=m/v, mass- scale, volume- graduated cylinder
• Crystal shape
• Cleavage and fracture
• Special properties: calcite, double vision

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