Whewellite

Whewellite

A white Whewellite crystal from Schlema, Germany
General
Category Oxalate mineral
Formula
(repeating unit)		 CaC2O4·H2O
Strunz classification 10.AB.45
Crystal system Monoclinic
Crystal class Prismatic (2/m)
(same H-M symbol)
Identification
References [1][2][3]

Whewellite is a mineral, hydrated calcium oxalate, formula CaC2O4·H2O. Because of its organic content it is thought to have an indirect biological origin; this hypothesis is supported by its presence in coal and sedimentary nodules. 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 was named after William Whewell (1794–1866), an English polymath, naturalist and scientist, professor of moral philosophy at Cambridge and inventor of the system of crystallographic indexing.

Whewellite heat decomposition

Whewellite (calcium oxalate monohydrate) heat decomposition mass curve

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

References

  1. ↑ Whewellite: mindat.org
  2. ↑ Webmineral.com
  3. ↑ Handbook of Mineralogy
Wikimedia Commons has media related to Whewellite.

See also

List of minerals named after people

List of minerals (complete)

This article is issued from Wikipedia - version of the 12/4/2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.