Igneous Rocks

1. Minerals A. can be liquids B. are organicC. are inorganic D. have no crystal structure

2. is a measure of how easily a mineral is scratched.A. luster B. cleavageC. hardness D. fracture

3. The color of a minerals powder on an unglazed porcelain tile is .A. luster B. hardnessC. density D. streak

4. When halite breaks it displays .A. fracture B. cleavageC. luster D. crystal form

5. Halite forms crystals.A. triclinic B. monoclinicC. hexagonal D. cubic

ReviewReviewMinerals Identifying minerals

Igneous RocksIgneous RocksRocks formed from melted minerals

Igneous RocksIgneous RocksSome have crystalsSlow cooling = “large” crystals –Granite

Granite

Igneous RocksIgneous RocksFast cooling = “small” crystals - Basalt

Basalt

Granite Basalt

Igneous RocksIgneous RocksExtra fast cooling = no crystals

Obsidian: Volcanic, “Glassy”

Pumice: Volcanic, “Frothy”Pumice: Volcanic, “Frothy”

Krakatoa Island 1883

Pumice: Volcanic, “Frothy”

Mt. St. Helens 1980