Brushite
Brushite (white) on montmorillonite
General
CategoryPhosphate mineral
Formula
(repeating unit)		CaHPO4 · 2 H2O
IMA symbolBsh[1]
Strunz classification8.CJ.50
Crystal systemMonoclinic
Space groupIa (no. 9)
Unit cella = 6.265 Å, b = 15.19 Å,
c = 5.814 Å; β = 116.47°; Z = 4
Identification
ColorColorless to pale or ivory-yellow
Crystal habitPrismatic to tabular acicular crystals; typically powdery or earthy
CleavagePerfect on {010} and {001}
TenacityBrittle
Mohs scale hardness2.5
LusterVitreous, pearly on cleavages
DiaphaneityTransparent to translucent
Specific gravity2.328
Optical propertiesBiaxial (+)
Refractive indexnα = 1.539 – 1.540
nβ = 1.544 – 1.546
nγ = 1.551 – 1.552
Birefringenceδ = 0.012
2V angleMeasured: 59 to 87°
SolubilityReadily in HCl
Other characteristicsPiezoelectric
References[2][3][4][5][6]

Brushite is a phosphate mineral with the chemical formula CaHPO4·2H2O. Crystals of the pure compound belong to the monoclinic space group C2/c and are colorless.[2][5] It is the phosphate analogue of the arsenate pharmacolite.

Discovery and occurrence

Brushite was first described in 1865 for an occurrence on Aves Island, Nueva Esparta, Venezuela, and named for the American mineralogist George Jarvis Brush (1831–1912).[4] 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 runoff of fields which have received heavy fertilizer applications.[4] Associated minerals include tanarakite, ardealite, hydroxylapatite, variscite and gypsum.[2]

Brushite is the original precipitating material in calcium phosphate kidney stones.[7] It is also one of the minerals present in dental calculi.

References

  1. ↑ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. 1 2 3 Anthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W.; Nichols, Monte C., eds. (2000). "Brushite". Handbook of Mineralogy (PDF). Vol. IV (Arsenates, Phosphates, Vanadates). Chantilly, VA, US: Mineralogical Society of America. ISBN 0962209732. Archived from the original (PDF) on 2016-03-04.
  3. ↑ Brushite. Mineralienatlas]
  4. 1 2 3 Brushite. Mindat.org
  5. 1 2 Brishite. Webmineral
  6. ↑ Schofield, P. F.; Knight, K. S.; Houwen, J. A. M. van der; Valsami-Jones, E. (December 2004). "The role of hydrogen bonding in the thermal expansion and dehydration of brushite, di-calcium phosphate dihydrate". Physics and Chemistry of Minerals. 31 (9): 606–624. Bibcode:2004PCM....31..606S. doi:10.1007/s00269-004-0419-6. S2CID 94011250.
  7. ↑ "Brushite". Virtual Museum of Molecules and Minerals. Retrieved 22 December 2017.
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