Ottensite , Stibnite Locality: Qinglong (Dachang) Sb-Au deposit, Qinglong County, Qianxi'nan Autonomous Prefecture, Guizhou Province , China ( Locality at mindat.org ) Size: 21.9 x 14.8 x 9.0 cm. A relatively rich and relatively not-so-ugly-as-usual specimen of this new species, from the type and only location known so far. The stibnites measure to about an inch. Much of this material was lost before it was described, because it was "cleaned" off, and so few large specimens remained to be had. From the type locality, from the collection of Marcus Origlieri who helped analyse the new species. He tells me that this is the largest fine specimen showing rich ottensite, good stibnite, and matrix, which he had kept for his own collection. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Ottensite
Ottensite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula Na₃(Sb₂O₃)₃(SbS₃)·3H₂O.
It crystallizes in the hexagonal crystal system (space group P6_3). It is a member of the Cetineite structural group.
Key properties: Mohs hardness 3.5; specific gravity 4.14; Yellow-brown streak; Adamantine to vitreous luster; optically uniaxial.
IMA symbol Ots, IMA status: approved, named in 2006.
A supergene product of stibnite weathering in the oxidation zone.
It is found associated with Stibnite, fluorite (Qinglong); mopungite, brizziite, metastibnite, valentinite (Pereta).
The mineral was named to honor Berthold Ottens (b.1942) mineral collector and dealer from Spiegelau, Germany and expert on Chinese minerals.