BISMUTH
Specimen bis-16
$ 25.00Dims: 1.2x0.9x0.6" (3.0x2.4x1.5cm)
Wt: 0.79 oz. (22.3g)
Rio Vilace, Dept. La Paz, Bolivia
This is a nugget of native bismuth. It has a weathered, slightly tumbled appearance. The core of the specimen is a porous, black mineral somewhat looking like goethite. Perhaps it is an oxide of bismuth. There is also a reddish-brown mineral (perhaps limonite), and some tiny crystals that may be calcite. There are also several thin, crystalline crusts of chalcopyrite. As the elemental bismuth appears on the outside of the black core, and the transition between them is smooth, I suspect they are related (and one is an alteration product of the other).