Brushite

Brushite
Brushite
	Brushite (white) on montmorillonite
General
Category	Phosphate mineral
Formula; (repeating unit)	CaHPO4 · 2 H2O
Strunz classification	8.CJ.50
Crystal system	Monoclinic
Space group	Ia (no. 9)
Unit cell	a = 6.265 Å, b = 15.19 Å, ; c = 5.814 Å; β = 116.47°; Z = 4
Identification
Color	Colorless to pale or ivory-yellow
Crystal habit	Prismatic to tabular acicular crystals; typically powdery or earthy
Cleavage	Perfect on {010} and {001}
Tenacity	Brittle
Mohs scale hardness	2.5
Luster	Vitreous, pearly on cleavages
Diaphaneity	Transparent to translucent
Specific gravity	2.328
Optical properties	Biaxial (+)
Refractive index	nα = 1.539 – 1.540 ; nβ = 1.544 – 1.546 ; nγ = 1.551 – 1.552
Birefringence	δ = 0.012
2V angle	Measured: 59 to 87°
Solubility	Readily in HCl
Other characteristics	Piezoelectric
References

Brushite is a phosphate mineral with the chemical formula Ca HPO₄·2H₂O. Crystals of the pure compound belong to the monoclinic space group C2/c and are colorless.^[1]^[4] 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).^[3] 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.^[3] Associated minerals include tanarakite, ardealite, hydroxylapatite, variscite and gypsum.^[1]

Brushite is the original precipitating material in calcium phosphate kidney stones.^[6] It is also one of the minerals present in dental calculi.

References[]

^ ^a ^b ^c 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.
^ Brushite. Mineralienatlas]
^ ^a ^b ^c Brushite. Mindat.org
^ ^a ^b Brishite. Webmineral
^ 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. doi:10.1007/s00269-004-0419-6.
^ "Brushite". Virtual Museum of Molecules and Minerals. Retrieved 22 December 2017.

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[HBM-1] 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.

[2] Brushite. Mineralienatlas]

[Mindat-3] Brushite. Mindat.org

[Webmin-4] Brishite. Webmineral

[5] 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. doi:10.1007/s00269-004-0419-6.

[6] "Brushite". Virtual Museum of Molecules and Minerals. Retrieved 22 December 2017.

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