This is a crystal of olivine within the igneous rock basalt.
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Image from: Andrew Alden, About.com Geology Guide
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Olivine looks like little green crystals. It is typically found in some igneous and metamorphic rocks. Often the crystals are so small that you need to use your hand lens or magnifying glass to see them clearly.
- Shape: Orthorhombic (usually a many-sided prism that has an overall sphere shape)
- Luster: Greasy
- Color: Green (but sometimes yellow or brown)
- Streak: White
- Hardness: 6.5-7 on Mohs Hardness Scale
- Cleavage: Yes, but the crystals do not break easily along it
- Fracture: Conchoidal, brittle
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TES XXVI, 3 fall 2010
The Fall 2010 issue of The Earth Scientist
, focuses on rocks and minerals, including articles on minerals and mining, the use of minerals in society, and rare earth minerals, and includes 3 posters!
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