Hornblende, a type of amphibole
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Find out how to identify minerals (...and learn what shape, luster, color, streak, hardness, cleavage and fracture are all about!)
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There are several different minerals within the amphibole group, but the most common type is hornblende. You can find small crystals of hornblende in many types of igneous rocks. They often look like little dark specks. Use your hand lens or magnifying glass to see the crystal shapes.
- Shape: Monoclinic (crystals look like short, six-sided columns)
- Luster: Glassy or milky
- Color: Black or dark green, translucent to opaque
- Streak: Grey-green or grey-brown
- Hardness: 5-6 on Mohs Hardness Scale
- Cleavage: Two planes that meet at a 124-degree angle
- Fracture: Uneven brittle fracture
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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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