Bayldonite

Bayldonite
Bayldonite, Tsumeb, Namibia
General
Category	Arsenate minerals
Formula (repeating unit)	PbCu3(AsO4)2(OH)2
Strunz classification	8.BH.45
Crystal system	Monoclinic
Crystal class	Prismatic (2/m) (same H-M symbol)
Space group	C2/c
Identification
Color	Green, apple-green
Crystal habit	Mammillary crust
Mohs scale hardness	4½
Luster	Resinous
Density	5.24–5.65 g/cm3 (measured), 5.707 g/cm3 (calculated)
References

Bayldonite (BAIL-done-ite) is a rare secondary mineral with the chemical formula PbCu₃(AsO₄)₂(OH)₂. It was first discovered in Penberthy Croft Mine, Cornwall, England, United Kingdom. It is named after its discoverer, John Bayldon (1837(8) – 1872). Specimens are also found in Tsumeb, Namibia, and Arizona, United States. It is sometimes used a gemstone.