
Basalt
Basalt is an aphanitic extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron exposed at or very near the surface of a rocky planet or moon.
Colors It Comes In - Dark Grey to Black and Dull Burgundy To Brown
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Fracture - (1) Colonnade, (2) Entablature, (3) Horizontal fractures near flow tops, (4) Conchoidal
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Shape - Variety Of Sizes, Column-Like, Hexagonal
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Luster - Dull
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Texture - Fine-grained, Aphanitic
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Streak - White to Grey
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Locality - In the USA, Basalt is widespread in Hawaii, Snake Plain River, and Columbia Basalt. Also, notable deposits occur in California, Minnesota, Texas, New England, and many other states.
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Where It Can Be Found - Basalt is one of the most popular rock types, covering more than 70% of the Earth's surface. It forms in many places, including mid-ocean ridges, island arcs, ocean islands, rifting valleys, and back-arc basins.
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Hardness On The Mohs Scale - 5 To 6 Out Of 10