This is the raw lead-gray bismuthinite specimen with feldspar. Dimensions: 3.6 x 2.1 x 1.3″ (9.2 x 5.4 x 3.4cm). Weight — 10.1oz (285 grams). Origin: Russia, Transbaikalia.
Some information about bismuthinite:
Bismuthinite is a mineral consisting of bismuth sulfide (Bi2S3). It is an important ore for bismuth. The crystals are steel-grey to off-white with a metallic luster. It is soft enough to be scratched with a fingernail and rather dense.
It occurs in hydrothermal veins with tourmaline-bearing copper veins associated with granite, in some high temperature gold veins, and in recent volcanic exhalation deposits.
It was first reported in 1832 from the mines of Potosí, Bolivia.