Whewellite/ˈhjuːəlaɪt/ is a mineral, hydrated calcium oxalate, formula CaC2O4·H2O.[6] Because of its organic content it is thought to have an indirect biological origin; this hypothesis is supported by its presence in coal and sedimentarynodules. However, it has also been found in hydrothermal deposits where a biological source appears improbable. For this reason, it may be classed as a true mineral.
Whewellite, or at least crystalline calcium oxalate, does also arise from biological sources. Small crystals or flakes of it are sometimes found on the surfaces of some cacti, and kidney stones frequently have the same composition.
^"whewellite". Merriam-Webster Dictionary. Retrieved 30 May 2024.
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Bibliography
Palache, P.; Berman H.; Frondel, C. (1960). "Dana's System of Mineralogy, Volume II: Halides, Nitrates, Borates, Carbonates, Sulfates, Phosphates, Arsenates, Tungstates, Molybdates, Etc. (Seventh Edition)" John Wiley and Sons, Inc., New York, pp. 1099–1101.