Germanate, krieselite may be considered as a gallium-bearing mineral because, although the IMA formula does not include Ga, generally Ga substitutes for some Al.
Specific gravity: 4.069 calculated
Hardness: 5½ to 6½
Colour: Beige to white
Luminescence: Not fluorescent under UV
Common impurities: C
Krieselite was approved in 2003 but to date (July 2022) it has been reported only from the type locality.
At the type locality, the Tsumeb Mine, Tsumeb, Oshikoto Region, Namibia, krieselite occurs in tennantite-chalcocite-galena-germanite ore. It forms hemispherical aggregates, up to 200 μm, and fibrous crusts, associated with quartz, wulfenite, anglesite and graphite. Fibres are up to 50 × 5 μm and form wedge-shaped aggregates of fine lamellae. (AM 96.1656). At the 29th level of the mine krieselite was associated with schneiderhöhnite and stottite (HOM).
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