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www.mineralgallery.co.za Minerals P-T |
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Sturmanite |
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Name
Sturmanite
Chemistry
Ca6(Fe,AL,Mn)2(So4)2[B(OH)4](OH)12-26H2O, Hydrated Calcium Iron Aluminum Manganese Sulfate Tetrahydroxoborate Hydroxide
Uses
As a mineral specimen
Color
Bright to dull yellow.
Hardness
2.5
Specific gravity
1.4-1.8 Very light. It is almost just water
Sturmanite is a mineral consist of almost just water and is thus very sensitive to heat and dryness.
It should not be displayed in full sun or under a strong UV light. It will discolor. The crystals are hexagonal. Usually with interesting terminations. It can be confused with Ettringite which is very similar.
This is a rare mineral and good specimens often fetch higher prices.
Sturmanite was described as a new mineral from the Kalahari Manganese field (see Peacor et al 1983) Some controversy surrounds this mineral's type-locality, which was given as Black Rock, but no specimens have ever been recorded from this mine, and the specimens must have originated from one of the other nearby mines. A close morphological and chemical similarity to ettringite and charlesite, which are also found in the manganese field, has added to the confusion of accurately identifying these minerals. Hexagonal, prismatic crystals up to 15 cm in length are known. N'Chwaning II mine is the premier locality for sturmanites where during 1982-1983 excellent specimens were collected.
