Yellow crystals of the rare bismuth molybdate mineral koechinite on matrix of blue chrysocolla. From: Inspiration Mine, Gila County, Arizona, United States of America. — Photo: David Hospital · CC BY-SA 4.0
Koechlinite
Koechlinite is an IMA-recognized mineral species in the molybdate class, with the chemical formula Bi₂MoO₆.
It crystallizes in the orthorhombic crystal system (space group Pca2_1).
Key properties: specific gravity 8.26; Pale greenish yellow streak; Silky luster; optically biaxial.
IMA symbol Kcl, grandfathered status — known before the IMA’s founding, named in 1914.
Found as a rare alteration product in the oxidation zone of Bi–Mo deposits.
It is found associated with Bismuth, skutterudite, quartz (Daniel mine, Schneeberg, Germany); molybdenite, bismuthinite, aikinite, bismite, wulfenite, quartz (Torgovsk mine, Russia).
The mineral was named to honor Rudolf Ignatz Koechlin (1862–1939), Austrian mineralogist and Curator of the Vienna Natural History Museum, Vienna, Austria.