Description
This is a classic Trepča combination with Bournonite, Pyrite and Calcite, The steel-gray striated crystals of Bournonite, “Rädelerz” are to 0.6 cm tall and display a nice metallic luster. Pyrite crystals are acicular and brassy in color, while the stubby roundish Calcite crystals are colorless-whitish and translucent. Some of the later species has crystals with perfect nail head (also called “Mercedes star”) terminations.
BTW, Rädelerz is a term used by German miners for "cog wheel ore" in allusion to the cyclic twinned crystals that resemble cog wheels. Look at the piece and you get it!