Outstanding white acicular crystals of the rare aluminium arsenate bulachite on a contrasting matrix. From: Sa Malesa, Sa Bidda Beccia, Sarroch, Cagliari Province, Sardinia, Italy. — Photo: David Hospital · CC BY-SA 4.0
Bulachite
Bulachite is an IMA-recognized mineral species in the arsenate class, with the chemical formula Al₆(AsO₄)₃(OH)₉(H₂O)₄·2H₂O.
It crystallizes in the orthorhombic crystal system. It is a member of the Bulachite structural group.
Key properties: Mohs hardness 2; specific gravity 2.6; Satiny luster; optically biaxial.
IMA symbol Buh, IMA status: approved, named in 1982.
Initially found on two museum specimens collected on mine dumps.
It is found associated with Arsenocrandallite, malachite, azurite, barian pharmacosiderite, goethite, quartz.
The name refers to the occurrence at Neubulach, Germany.