{{Short description|Calcium phosphate mineral}} {{Distinguish|Brucite|Magnesium hydroxide}} {{Infobox mineral | image = Brushite, Montmorillonite-445846.jpg | caption = Brushite (white) on montmorillonite | name = Brushite | category = Phosphate mineral | formula = {{chem2|CaHPO4 * 2 H2O}} | IMAsymbol=Bsh<ref>{{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}}</ref> | strunz = 8.CJ.50 | system = Monoclinic | symmetry = ''Ia'' (no. 9) | unit cell = a = 6.265&nbsp;Å, b = 15.19&nbsp;Å, <br/>c = 5.814&nbsp;Å; β = 116.47°; Z&nbsp;=&nbsp;4 | color = Colorless to pale or ivory-yellow | habit = Prismatic to tabular acicular crystals; typically powdery or earthy | twinning = | cleavage = Perfect on {010} and {001} | fracture = | tenacity = Brittle | mohs = 2.5 | luster = Vitreous, pearly on cleavages | streak = | diaphaneity = Transparent to translucent | gravity = 2.328 | density = | polish = | opticalprop = Biaxial (+) | refractive = n<sub>α</sub> = 1.539 – 1.540 <br>n<sub>β</sub> = 1.544 – 1.546 <br>n<sub>γ</sub> = 1.551 – 1.552 | birefringence = δ = 0.012 | pleochroism = | 2V = Measured: 59 to 87° | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = Readily in HCl | impurities = | alteration = | other = Piezoelectric | prop1 = | prop1text = | references = <ref name=HBM>{{cite book|editor1-last=Anthony|editor1-first=John W.|editor2-last=Bideaux|editor2-first=Richard A.|editor3-last=Bladh|editor3-first=Kenneth W.|editor4-last=Nichols|editor4-first=Monte C.|title= Handbook of Mineralogy|publisher=Mineralogical Society of America|place=Chantilly, VA, US|url=http://www.handbookofmineralogy.com/pdfs/brushite.pdf |chapter=Brushite|isbn=0962209732 |volume=IV (Arsenates, Phosphates, Vanadates)|year=2000|archive-url=https://web.archive.org/web/20160304052347/http://www.handbookofmineralogy.com/pdfs/brushite.pdf|archive-date=2016-03-04}}</ref><ref>[https://www.mineralienatlas.de/lexikon/index.php/MineralData?mineral=Brushite Brushite]. Mineralienatlas]</ref><ref name=Mindat>[http://www.mindat.org/min-793.html Brushite]. Mindat.org</ref><ref name=Webmin/><ref>{{cite journal |last1=Schofield |first1=P. F. |last2=Knight |first2=K. S. |last3=Houwen |first3=J. A. M. van der |last4=Valsami-Jones |first4=E. |title=The role of hydrogen bonding in the thermal expansion and dehydration of brushite, di-calcium phosphate dihydrate |journal=Physics and Chemistry of Minerals |date=December 2004 |volume=31 |issue=9 |pages=606–624 |doi=10.1007/s00269-004-0419-6|bibcode=2004PCM....31..606S |s2cid=94011250 }}</ref> }} '''Brushite''' is a phosphate mineral with the chemical formula {{chem2|CaHPO4*2H2O}}. Crystals of the pure compound belong to the monoclinic space group C2/c and are colorless.<ref name=HBM/><ref name=Webmin>[http://webmineral.com/data/Brushite.shtml Brishite]. Webmineral</ref> It is the phosphate analogue of the arsenate pharmacolite.

==Discovery and occurrence== Brushite was first described in 1865 as an occurrence on Aves Island, Nueva Esparta, Venezuela, and named for the American mineralogist George Jarvis Brush (1831–1912).<ref name=Mindat/> It is believed to be a precursor of apatite and is found in guano-rich caves, formed by the interaction of guano with calcite and clay at a low pH. It occurs in phosphorite deposits and forms encrustations on old bones. It may result from the runoff of fields which have received heavy fertilizer applications.<ref name=Mindat/> Associated minerals include taranakite, ardealite, hydroxylapatite, variscite and gypsum.<ref name=HBM/>

Brushite is the original precipitating material in calcium phosphate kidney stones.<ref>{{cite web|title=Brushite|url=https://virtual-museum.soils.wisc.edu/display/brushite/|website=Virtual Museum of Molecules and Minerals|accessdate=22 December 2017}}</ref> It is also one of the minerals present in dental calculi.

==References== {{reflist}}

{{Phosphate-mineral-stub}}

Category:Calcium minerals Category:Phosphate minerals Category:Cave minerals Category:Monoclinic minerals Category:Minerals in space group 9