Middlebackite
A copper oxalate-hydroxide organic mineral discovered in a boulder from South Australia's Iron Monarch quarry in 1990.
Intro adapted from Wikipedia (CC BY-SA).
Middlebackite is an IMA-recognized mineral species in the organic mineral class, with the chemical formula Cu₂C₂O₄(OH)₂.
It crystallizes in the monoclinic crystal system (space group P2_1/c). It is a member of the Not in a structural group, Oxalate structural group.
Key properties: Mohs hardness 2; specific gravity 3.64; Pale blue streak; Vitreous luster; optically biaxial.
IMA symbol Mbk, IMA status: approved, named in 2015.
A supergene mineral in a weathered Precambrian manganiferous sedimentary iron ore deposit. A source of oxalate was probably decaying organic matter.
It is found associated with Atacamite, mottramite.
The name refers to the Middleback Range, in which the Iron Monarch quarry is located.