Colemanite Archives - Cochise College Geology

Colemanite

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Chemical Group: Borate

Chemical Formula: Ca₂B₆O₁₁.5H₂O

Color: Colorless, white, yellowish, grayish Streak: White

Hardness: 4.5 Specific Gravity: 2.42

Fracture: Uneven Tenacity: Brittle

Luster: Vitreous Transparency: Transparent to translucent

Cleavage: (010) perfect, (001) distinct

Crystal Forms: Monoclinic system. Often massive, granular

Mineral Associations: Other borate minerals

Uses: Used in producing borate compounds

Occurrences: California borax deposits

Toxicity: When-swallowed: high When-inhaled: moderate

Additional Information: Colemanite is a hydrous calcium borate. The water content of the Colemanite provides the basis for an interesting story. A prospector in the Death Valley area of California decided to make a campfire to cook his supper. He gathered up rocks to surround the campfire and then proceeded to cook his supper. As the fire started to warm up the rocks, which turned out to be colemanite, the rocks started exploding and the prospector ran for cover. The supper was filled with rock fragments and was ruined. The culprit was the water content of colemanite which converted to steam as the rocks were baked.

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Photos

Colemanite 1 2 3 4 5 6

colemanite-light brown spikey crystals — Colemanite - Light Brown Spikey Crystals

colemanite-light brown-massive — Colemanite - Light Brown - Massive

colemanite-light brown-massive-close view — Colemanite - Light Brown - Massive - Close View

colemanite-white crystals — Colemanite - White Crystals

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