# Whewellite
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> Markdown URL: https://mediated.wiki/source/Whewellite.md
> Source: https://en.wikipedia.org/wiki/Whewellite
> Source revision: 1308963091
> License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/)
{{Short description|Mineral}}
{{Infobox mineral
| name = Whewellite
| boxwidth =
| image = Whewellite-md82a.jpg
| alt =
| caption = A white Whewellite crystal from Schlema, Germany
| category = [Oxalate minerals](/source/Oxalate_minerals)
| formula = CaC2O4·H2O
| IMAsymbol = Whe[{{Cite journal|last=Warr|first=L.N.|date=2021|title=IMA–CNMNC approved mineral symbols|journal=Mineralogical Magazine|volume=85|issue=3|pages=291–320|doi=10.1180/mgm.2021.43|bibcode=2021MinM...85..291W|s2cid=235729616|doi-access=free}}]
| molweight =
| strunz = 10.AB.45
| dana =
| system = [Monoclinic](/source/Monoclinic)
| class = Prismatic (2/m)
(same [H-M symbol](/source/H-M_symbol))
| symmetry = ''P21/c'' (no. 14)
| unit cell =
| color = Colorless, yellowish, brownish
| colour =
| habit = Equant or stout prismatic crystals
| twinning = ''e'' {{{overline|1}}01} twin plane
| cleavage = {{{overline|1}}01} good, {010} imperfect, {001} indistinct, {110} indistinct
| fracture = Conchoidal
| tenacity = Brittle
| mohs = 2.5–3
| luster = Vitreous to pearly
| streak =
| diaphaneity = Transparent
| gravity = 2.23
| density =
| polish =
| opticalprop = Biaxial (+), colorless (transmitted light)
| refractive =
| birefringence =
| pleochroism =
| 2V =
| dispersion =
| extinction =
| length fast/slow =
| fluorescence =
| absorption =
| melt =
| fusibility =
| diagnostic =
| solubility = Insoluble in water, soluble in acids
| impurities =
| alteration =
| other =
| prop1 =
| prop1text =
| references = [[http://www.mindat.org/min-4276.html Whewellite: mindat.org]][[http://www.webmineral.com/data/Whewellite.shtml Webmineral.com]][{{Cite web |url=http://www.handbookofmineralogy.com/pdfs/whewellite.pdf |title=''Handbook of Mineralogy'' |access-date=2011-05-15 |archive-date=2016-03-03 |archive-url=https://web.archive.org/web/20160303171459/http://www.handbookofmineralogy.com/pdfs/whewellite.pdf |url-status=dead }}][{{cite journal |last1=Tazzoli |first1=V. |last2=Domeneghetti |first2=M.C. |journal=American Mineralogist |volume=65 |year=1980 |pages=327–334 |title=The crystal structures of whewellite and weddellite: re-examination and comparison |url=https://pubs.geoscienceworld.org/msa/ammin/article-abstract/65/3-4/327/41138/The-crystal-structures-of-whewellite-and?redirectedFrom=fulltext |access-date=31 December 2020}}]
}}
'''Whewellite''' {{IPAc-en|ˈ|h|juː|ə|l|aɪ|t}} is a mineral, hydrated [calcium oxalate](/source/calcium_oxalate), formula [Ca](/source/calcium) [C](/source/carbon)2[O](/source/oxygen)4·[H2O](/source/water).[{{cite web |title= whewellite |publisher= Merriam-Webster Dictionary|url= https://www.merriam-webster.com/dictionary/whewellite |accessdate= 30 May 2024}}] Because of its organic content it is thought to have an indirect biological origin; this hypothesis is supported by its presence in [coal](/source/coal) and [sedimentary](/source/sedimentary) [nodules](/source/Nodule_(geology)). However, it has also been found in [hydrothermal](/source/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](/source/cacti), and [kidney stones](/source/kidney_stones) frequently have the same composition.
Whewellite was named after [William Whewell](/source/William_Whewell) (1794–1866), an [English](/source/England) [polymath](/source/polymath), [naturalist](/source/Natural_history) and [scientist](/source/scientist), professor of moral philosophy at [Cambridge](/source/Cambridge_University) and inventor of the system of crystallographic indexing.