Calumetite

Calumetite; Jeff Weissman / Photographic Guide to Mineral Species at Web Mineral: Link

Description

A light blue copper corrosion product that rarely occurs as a mineral. As a mineral, it was discovered in 1963 at the Centennial Miner near Calumet, Michigan. Calumetite has been identified as a copper corrosion product on bronzes (Scott 2000).

Physical and Chemical Properties

• Composition = Cu(OH, Cl)₂ - 2(H₂O)
• Description = azure to light blue crystals (orthorhombic)
• Streak = bluish-white
• Luster = pearly
• Hardness = 2

Resources and Citations

• David Scott, 'A Review of Copper Chlorides and Related Salts in Bronze Corrosion and as Painting Pigments'. Studies in Conservation, 45, 39-54, (2000).

• WebMineral: Calumentite

• Wikipedia: Calumentite

• Mindat: Calumentite