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www.mineralgallery.co.za Minerals A-E |
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Erythrite |
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Name
Erythrite
Chemistry
Co3(AsO4)2.8H2O. Cobalt and nickel substitutes for one another to form a complete series; significant amounts of calcium, zinc, ferrous iron and magnesium can also be substituted for these elements.
Uses
As a mineral specimen, and as an indicator in prospecting for cobalt and nickel.
Color
purple-red, pink-red, violet. Powdered erythrite will turn lavender blue on heating.
Hardness
.15 to 2.5
Specific gravity
3.07
Crystal system
monoclinic. crystal form: prism, nodular. Crystals are prismatic to accicular and flattened often deeply atriated, but are usually rare and poorly formed; usually in radiating groups or crusts; often in globular or reniform shapes with course fibrous interior, also earthy or powdery.
Accompanied by:
Pharmacolite, Annabergite, Chloanthite
Luster
adamantine, pearly.
Cleavage
perfect on (010)
Streak
pink-red
Similar to:
Chalotrichite
Erythrite was very rare at Tsumeb.
Erythrite is also known as cobalt bloom. It is a rare secondary mineral, usually formed by the alteration by wheathering of cobalt and nickel arsenides in the oxidised zone of some ore deposits.
