Chemical Formula: CuPbSbS3

Chemical Name: Copper Lead Antimony Sulphide

Mineral Class: Sulphide

Mineral Notes: Bournonite is a popular collector mineral because of the striking silvery-grey crystals which have a strong tendency to form radiating (cogwheel-like) aggregates. For this reason Cornish miners, where particularly striking specimens were once found, knew the mineral as cogwheel ore. Similarly, in Germany the mineral is known as Radelrz, or wheel ore.  

Description: Well-formed cog-wheel crystals of Bournonite nestling amongst columnar Quartz crystals. The form is very characteristic of the mineral and can esily be seen, although magnification will give better viewing. The mineral has a very strong metallic luster which produces a very attractive contrast against the clear Quartz. There are several brassy Chalcopyrite crystals that complete the specimen.

Location: Herja Mine, Romania.