Raspberry prisms. These beautiful crystals are Erythrite, a secondary mineral made by watery alterat
Raspberry prisms.These beautiful crystals are Erythrite, a secondary mineral made by watery alteration and oxidation of cobalt arsenic minerals. It is a hydrated cobalt arsenate, incorporating water in its structure, and crystallises in the monoclinic crystal system. It is also known as cobalt bloom, often occuring as a coating on the minerals it is produced from. Well formed prisms are rare, since it usually occurs as crusts. It forms a solid solution with nickel arsenate, with cobalt and nickel fitting into the crystal structure interchangeably. Cobalt imparts strong colours to minerals, depending on how it fits into the crystal, and is most often found in deep blue glasses.It was first described in 1832 by a French mineralogist, from a location in Germany, and named after the Greek word for red. While not worth mining for metals in itself, it is an indicator mineral for cobalt and native silver deposits. This area produces the best crystals found so far worldwide. Other famous locations include Ontario, the Czech republic, Cornwall in England and a couple of places in Australia. It is too soft for faceting, but much loved by mineral collectors.LozLocation: Aghbar Mine, Bou Azzer, Tazenakht, Ouarzazate Prov., Morocco.Size: 7x5x2 Cm.Image credit: Rob Lavinsky/irocks.comFurther pictures: http://www.johnbetts-fineminerals.com/jhbnyc/mineralmuseum/gallery.php?init=Erythritehttp://www.mindat.org/min-1407.htmlhttp://webmineral.com/data/Erythrite.shtmlhttp://www.minerals.net/mineral/erythrite.aspxhttp://www.galleries.com/Erythrite -- source link
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