Metallic grey single crystal of the extremely rare Ag-Cu-Bi mineral arcubisite from the type locality in Ivigtut (Ivigtut, Ivittuut, Arsuk Fjord, Sermersooq, Greenland). Ex.Vandenbroucke Museum collection from Waregem, Belgium. — Photo: David Hospital · CC BY-SA 4.0
Arcubisite
Arcubisite (Ag6CuBiS4) is a sulfosalt mineral occurring with cryolite in Greenland. It is named after its composition (ARgentum, CUprum, and BISmuth). Its IMA symbol is Acb.
Intro adapted from Wikipedia (CC BY-SA).
Arcubisite is an IMA-recognized mineral species in the sulfosalt class, with the chemical formula Ag₆CuBiS₄.
Key properties: Metallic. Anisotropism: Distinct in air, strong in oil, cream to bluish green. R1 –R2: (400) —, (420) — luster.
IMA symbol Acb, IMA status: approved, named in 1973.
Found in a cryolite deposit.
It is found associated with Galena, hessite, aikinite, matildite, berryite, tellurian canfieldite, acanthite, bismuth, quartz, fluorite, cryolite.
The name refers to the major metallic elements in the mineral: ARgentum, silver; CUprum, copper; BISmuth and Sulfur.