Carminite

It's advisable to handle carminite carefully to avoid generating dust and wash hands thoroughly afterward. When cutting or polishing carminite, wear a dust mask to prevent inhaling heavy metal particles. Store carminite in a sealed container in a well-ventilated area, away from children and pets. For those involved in crystal healing, never put it in your mouth.

Carminite is fairly soft, with a Mohs hardness of ​3 ⁄2, between that of calcite and fluorite. Because of the lead content it is heavy, with specific gravity of 5.03 - 5.18, although specimens from Mapimi are less dense at 4.10. Cleavage is distinct in one direction parallel to the c axis. The mineral is slowly soluble in hydrochloric acid (HCl) with the separation of lead(II) chloride (PbCl2) and totally soluble in nitric acid (HNO3). Carminite is not radioactive and no piezoelectric effect has been detected.

Crystals have been found up to 2 cm long, though most are smaller. They are typically bladed, elongated along the c axis and flattened perpendicular to the b axis. They also occur as acicular crystals, in spherical or tufted aggregates and as fibrous or drusy masses. The crystals are a characteristic carmine red colour, hence the name, and they are also red in transmitted light. They are translucent with a vitreous lustre and a reddish yellow streak.

Carminite is formed as an uncommon alteration product of arsenopyrite (FeAsS) in the oxidized zones of some lead-bearing deposits. Common associates are wulfenite, scorodite, plumbojarosite, mimetite, dussertite, cerussite, beudantite, bayldonite, arseniosiderite and anglesite. The type locality is the Louise Mine, Bürdenbach, Altenkirchen, Wied Iron Spar District, Westerwald, Rhineland-Palatinate, Germany where it is associated with beudantite. At the Hingston Down Consols mine in Cornwall, England, carminite occurs with scorodite, mimetite and pharmacosiderite. The ores of the Ojuela Mine, Mexico, are replacement deposits in limestone and consist of galena, sphalerite, pyrite, and arsenopyrite in a matrix of quartz, dolomite and fluorite. Arsenopyrite is abundant. On a dump near the north shaft blocks of massive scorodite containing seams and pockets of arseniosiderite and small areas of dussertite and carminite have been found. Carminite also occurs as masses mixed with cerussite, anglesite and plumbojarosite. It is almost always intimately associated with arseniosiderite and dussertite.

Carminite belongs to the orthorhombic crystal class (2/m 2/m 2/m) and has space group C ccm or C cc2. The structure consists of linked octahedra of iron surrounded by oxygen and hydroxyl which are aligned parallel to the c axis. They are connected together in the direction of the an axis by arsenate tetrahedra (arsenic surrounded by 4 oxygen). Coordination about the lead atoms is eight-fold. The edges of the unit cell have lengths a = 16.59 Å, b = 7.58 Å and c = 12.295 Å. There are 8 formula units in each unit cell (Z = 8).

Carminite is used as a minor source of lead in some areas. While lead has been banned from many applications due to its toxicity, it is still used for car batteries, weights, radiation protection, and in stained windows.