Calclacite
A rare organic mineral of calcium, chloride and acetate — its name spells out its ingredients.
Intro adapted from Wikipedia (CC BY-SA).
Calclacite is an IMA-recognized mineral species in the organic mineral class, with the chemical formula Ca(CH₃COO)Cl·5H₂O.
It crystallizes in the monoclinic crystal system (space group P2_1/a). It is a member of the Acetate structural group.
Key properties: specific gravity 1.5; Silky in aggregates luster; optically biaxial.
IMA symbol Calc, grandfathered status — known before the IMA’s founding, named in 1945.
Forms on calcareous rock and fossil specimens and pottery sherds thorough the action of acetic acid derived from oak storage cabinets.
It is found associated with Unspecified efflorescent salts.
The name comes from the composition, CALcium, chlorine, CL, and ACetate.