Aurichalcite
General
Category	Carbonate mineral
Chemical formula	(Zn,Cu)5(CO3)2(OH)6
Identification
Color	pale green, greenish blue, sky blue
Crystal habit	Acicular to druzy encrustations
Crystal system	Monoclinic-prismatic
Cleavage	[010] Perfect
Fracture	Uneven
Mohs scale hardness	2
Luster	Pearly
Streak	Light blue
Specific gravity	3.64 - 3.9
Optical properties	Biaxial (-)
Refractive index	nα = 1.655 nβ = 1.740 nγ = 1.744
Birefringence	0.0890
Pleochroism	Weak colorless to pale green

Aurichalcite is a carbonate mineral, usually found as a secondary mineral in copper and zinc deposits. Its chemical formula is (Zn,Cu)₅(CO₃)₂(OH)₆. The zinc to copper ratio is about 5:4×←×←±.

Associated minerals include: rosasite, smithsonite, hemimorphite, hydrozincite, malachite and azurite.

It was first described in 1839 by Bottger who named the mineral for its zinc and copper content after the Greek όρειχαλκος, for "mountain brass" or "mountain copper", the name of a fabulous metal.

[edit] References

• Handbook of Mineralogy
• Mindat
• Webmineral data

Aurichalcite

Needle Crystals of Aurichalcite from Nevada, USA