Fused Wood-Ash Stones: Fairchildite (n. sp.) K2CO2CaCO2, Buetschliite (n. sp.) 3K2CO2 2CaCO2 6H2O and Calcite, CaCO2, Their Essential Components
Milton C and Axelrod J. 1947. Fused Wood-Ash Stones: Fairchildite (n. sp.) K2CO2CaCO2, Buetschliite (n. sp.) 3K2CO2 2CaCO2 6H2O and Calcite, CaCO2, Their Essential Components. American Mineralogist. 32:607-624
Stones found in the trunks of standing partly burned forest trees are produced by fusion and ensuing crystallization of the ash of the wood. Freshly formed stones consist essentially of a new mineral fairchildite, anhydrous potassium calcium carbonate, K2CO2 CaCO2. On wetting, or by atmospheric hydration, this is converted to buetschliite, a second new mineral, a hydrous potassium calcium carbonate, and calcite. On further leaching the buetschliite is decomposed to calcite with removal of the water-soluble potassium carbonate. The presence of the first three carbonates in wood-ash stones is established, and a general account of them with a review of pertinent literature is given. The artificial compounds corresponding to fairchildite and buetschliite were prepared and analyzed by Otto Buetschli in 1901-1905, but have not hitherto been reported in nature. Fairchildite is hexagonal and buetschliite is probably also hexagonal.