Carminite, PbFe3+2(AsO4)2(OH)2 (lead iron hydroxy arsenate), was only recognized as a separate mineral in the last fifty years. Before that it was often seen in — Photo: Nessa Eull · CC0
Carminite
A rare anhydrous lead-iron arsenate, structurally related to the phosphate palermoite.
Intro adapted from Wikipedia (CC BY-SA).
Carminite is an IMA-recognized mineral species in the arsenate class, with the chemical formula PbFe³⁺₂(AsO₄)₂(OH)₂.
It crystallizes in the orthorhombic crystal system (space group Cccm). It is a member of the Carminite structural group.
Key properties: Mohs hardness 3.5; specific gravity 5.03–5.18; typically red or brown; Reddish yellow streak; Vitreous, pearly on cleavages luster; refractive index 2.073; optically biaxial.
IMA symbol Cmt, grandfathered status — known before the IMA’s founding, named in 1850.
An uncommon alteration product of arsenopyrite in some oxidized lead-bearing mineral deposits.
It is found associated with Beudantite, scorodite, dussertite, arseniosiderite, bayldonite, mimetite, cerussite, anglesite, plumbojarosite, wulfenite.
The name refers to the characteristic carmine color.
Collections: Collector Favorites, Rare & Remarkable.