Aurichalcite
Image: Robert M. Lavinsky (CC BY-SA 3.0)
Mineral NameAurichalcite
Chemical Formula(Zn,Cu)5(CO3)2(OH)6
Mohs Hardness1
Crystal Systemmonoclinic
Lustersilky
Streak Colorpale greenish blue
Cleavageperfect on {100}
Fractureuneven
Specific Gravity3.6
Colorspale blue, greenish blue, light green
Transparencytransparent
Type LocalityCleopatra Mine, Bryant District (Hecla District), Beaverhead County, Montana, USA
Mineral Groupcarbonates
Usescollector
Associated Mineralsmalachite, azurite, smithsonite, hemimorphite, hydrozincite, calcite, limonite
Rarityuncommon
Description
This specimen features delicate, acicular to fibrous crystals of pale greenish-blue aurichalcite forming crusts and radiating aggregates on a brown, iron-rich matrix.
Geological Context
Aurichalcite is a secondary mineral that forms in the oxidized zones of zinc and copper ore deposits, typically as an alteration product of primary sulfide minerals in arid or semi-arid environments.
