Almost white crystal aggregates of the rare mineral kettnerite associated to an unknown green mineral. From Three Musketeers Mine, Ellsworth, La Paz County, Arizona, United States of America. — Photo: David Hospital · CC BY-SA 4.0
Kettnerite
Kettnerite is an IMA-recognized mineral species in the carbonate class, with the chemical formula CaBiO(CO₃)F.
It crystallizes in the orthorhombic crystal system (space group Pmmn). It is a member of the Bismutite structural group.
Key properties: specific gravity 5.8; optically biaxial.
IMA symbol Ket, grandfathered status — known before the IMA’s founding, named in 1956.
Found in a quartz vein cutting pegmatitic potassian feldspar (Krupka, Czech Republic).
It is found associated with Fluorite, bismuth, bismuthinite, hematite, topaz (Krupka, Czech Republic); perite, hemimorphite, embolite, fluorite, chrysocolla, quartz (Blue Bell claims.
The mineral was named to honor Radim Kettner (1891–1968), Professor of Geology, Charles University, Czech Republic.