Eskimoite , Gustavite Locality: Bockhart reservoir (Pochkar reservoir), Siglitz - Bockhart area, Gastein valley, Hohe Tauern Mts, Salzburg , Austria ( Locality at mindat.org ) Size: 2.9 x 2.9 x 1.3 cm. An extremely rich example of this silver, lead, bismuth sulfide in crystals to 0.2 mm embedded in the matrix and intimately associated with gustavite. There may be other minerals present such as Vikingite, Ourayite, Schirmerite, and Treasurite. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Gustavite
Gustavite is an IMA-recognized mineral species in the sulfosalt class, with the chemical formula AgPbBi₃S₆.
It crystallizes in the monoclinic crystal system (space group P2_1/c). It is a member of the Lillianite structural group.
Key properties: specific gravity 7.01.
IMA symbol Gus, IMA status: approved, named in 1967.
A rare mineral of hydrothermal origin; also in pegmatites.
It is found associated with Aikinite, bismuthinite, cosalite, pavonite, benjaminite, bismuth, chalcopyrite, tetrahedrite, pyrrhotite, stannite, arsenopyrite.
The mineral was named to honor Gustav Adolf Hageman (1842–1916), chemical engineer for the Cryolite Firm, Ivigtut, Greenland.