4.2 x 3.2 x 2.1 cm. Here is a lovely and extremely rare sample of the hydrated calcium sodium arsenate mcnearite from the type locality in Sainte Marie-aux-mines. This specific locality operated for a short time (from 1932 to 1940) and now is designated with archaeological mining district status, so collecting is not allowed. The vein system surrounding this mine had been worked since the middle of the 1500s. Despite the short time that Gabe Gottes was in production, it actually produced the type specimens for eight different species including mcnearite. This piece features pearl white patches of mcnearite sitting on host rock matrix. This piece is accompanied by a classic label from Josef Vajdak/Pequa Rare Minerals. You can read Joe's biography here: http://www.minrec.org/labels.asp?colid=1371 . — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Mcnearite
Mcnearite is an IMA-recognized mineral species in the arsenate class, with the chemical formula NaCa₅(AsO₄)(AsO₃OH)₄·4H₂O.
It crystallizes in the triclinic crystal system.
Key properties: specific gravity 2.6; Pearly luster; optically biaxial.
IMA symbol Mnr, IMA status: approved, named in 1980.
Found as a secondary mineral in the oxidized zone of an arsenic-bearing deposit.
It is found associated with Picropharmacolite, pharmacolite, guérinite, haidingerite.
The mineral was named to honor Elizabeth McNear, mineralogist and crystallographer, University of Geneva, Geneva, Switzerland.