Two yellow small specimens of the very rare cerium-lanthanum carbonate mineral calkinsite-(Ce) from the TL in Montana (Rocky Boy Stock Occurrence, Hill County, Montana, United States of America). Ex Vandenbroucke Museum collection from Waregem, Belgium. — Photo: David Hospital · CC BY-SA 4.0
Calkinsite-(Ce)
Calkinsite-(Ce) is an IMA-recognized mineral species in the carbonate class, with the chemical formula Ce₂(CO₃)₃·4H₂O.
It crystallizes in the orthorhombic crystal system (space group P2_122_1).
Key properties: Mohs hardness 2.5; specific gravity 3.28; optically biaxial.
IMA symbol Clk-Ce, IMA status: approved, named in 1953.
A weathering product closely in association with burbankite, in calcite veins cutting shonkinite in a composite stock (Big Sandy Creek, Montana, USA).
It is found associated with Burbankite, ancylite, lanthanite, barite, goethite, calcite, “biotite” (Big Sandy Creek, Montana, USA); barite, strontianite, pyrite (Vuoriyarvi massif.
The mineral was named to honor Frank Cathcart Calkins (1878–1974), geologist with the U.S. Geological Survey.