Mineral Species: Fornacite and Wulfenite 

Chemical Formula: Pb2Cu(AsO4)(CrO4)(OH)

Chemical Name: Lead Copper Arsenate Chromate Hydroxide

Mineral Class: Chromates

Mineral Notes: Fornacite is a rare mineral forming in the oxidized zones of some hydrothermal base-metal deposits. It is named after Lucien Louis Forneau (1867–1930), Colonial Governor of the French Congo.  

Description: Small, black tabular crystals of Fornacite amongst orange crystals of transparent Wulfenite. Although the latter are small, they are very lustrous. The contrast between the two minerals is quite striking but is best appreciated under magnification.

Location: Eagle Eye Mine, La Paz Co., Arizona, USA.