Antlerite

Mineral Cu3(SO4)(OH)4

About it

Nearly identical to brochantite by eye and needs testing to separate; it favours drier, more acidic ore zones. Was once the main copper ore at Chuquicamata in Chile; named for the Antler mine in Arizona.

Type
Mineral
Group
Sulfate, basic copper sulfate
Formula
Cu3(SO4)(OH)4
Hardness (Mohs)
3.5–4
Specific gravity
3.88–3.95
Streak
pale green
Lustre
vitreous (glassy)
Crystal system
Orthorhombic
Colours
emerald green, blackish green, light green
Transparency
transparent, translucent
Cleavage and fracture
perfect in one direction

Typical values: real specimens vary. For more, see mindat.org.