Whewellite

Whewellite is a mineral, hydrated calcium oxalate, formula CaC2O4&middot;H2O. Because of its organic content it is thought to have an indirect biological origin and this is supported by it being found in coal and sedimentary nodules. However, it has also been found in hydrothermal deposits where a biological source appears improbable. For this reason it can be classed as true mineral.

Whewellite, or at least crystalline calcium oxalate does also arise from natural sources. Small crytals or flakes are sometimes found forming on the surface of some cacti. Also some particularly unpleasant kidney stones are deposited as calcium oxalate.

Whewellite is named after William Whewell (1794-1866), an English mineralogist.

Whewellite heat decomposition
Whewellite is used as a thermogravimetric analysis standard due to its well known decomposition temperatures and products.

Whewellita Whewellite