Mineral Species: Stromeyerite

Chemical Formula: AgCuS

Chemical Name: Silver Copper Sulphide

Mineral Class: Sulphide

Mineral Notes: Stromeyerite forms in hydrothermal veins, most commonly by secondary processes, although it also forms as a primary mineral. It is named after Professor Friedrich Stromeyer (1776–1835), chemist and mineralogist, University of Gottingen, Germany, who first analysed the mineral.

Description: The body of this specimen is made of crystalline Stromeyerite. However these crystals are very small and are only seen individually when magnified. Embedded in the surface are small crystals of brassy Chalcopyrite. The contrast between the dark grey of the Stromeyerite and Chalcopyrite is very attractive, especially as the latter has a very pronounced metallic luster.

Location: Smeirrogarsk Mine, Altai, Russia.