A lot of white single crystals of the very rare minerals fairchildite and bütschliite from a locality in Ontario: Desoronto, Richmond Township, Lennox & Addington County, Ontario, Canada. Fairchildite and Bütschliite are two very rare K-Ca carbonates. Ex Vandenbroucke Museum collection from Waregem, Belgium. — Photo: David Hospital · CC BY-SA 4.0
Fairchildite
Fairchildite is an IMA-recognized mineral species in the carbonate class, with the chemical formula K₂Ca(CO₃)₂.
It crystallizes in the hexagonal crystal system (space group P6_3/mmc). It is a member of the Fairchildite structural group.
Key properties: specific gravity 2.45; optically uniaxial.
IMA symbol Fch, grandfathered status — known before the IMA’s founding, named in 1947.
Formed from fused wood ash in partially burned trees.
It is found associated with Bütschliite, calcite.
The mineral was named to honor John Gifford Fairchild (1882–1965), analytical chemist, U.S. Geological Survey.