Whitlockite

Whitlockite
An example of the mineral whitlockite on display at the Royal Ontario Museum. All whitlockite bears a strong resemblance to cooked fettucine with spinach sauce.
General
CategoryPhosphate minerals
Formula
(repeating unit)
Ca9(Mg,Fe++)(PO4)6(PO3OH)
IMA symbolWht[1]
Strunz classification8.AC.45
Crystal systemTrigonal
Crystal classDitrigonal pyramidal (3m)
H-M symbol: (3m)
Space groupR3c
Unit cella = 10.33, c = 37.103(5) [Å]; Z = 3
Identification
ColorColorless, gray-white, light pink, light yellow
Crystal habitrhombohedral crystals, often tabular, massive, microcrystalline crusts and as "cave pearls"
CleavageNone
FractureBrittle
TenacityBrittle
Mohs scale hardness5
LusterVitreous to resinous
StreakWhite
DiaphaneityTransparent
Density3.13
Optical propertiesUniaxial (−)
Refractive indexnω = 1.629 nε = 1.626
Birefringenceδ = 0.003
Other characteristicsPiezoelectric and pyroelectric
References[2][3][4]

Whitlockite is a mineral, an unusual form of calcium phosphate. Its formula is Ca9(MgFe)(PO4)6PO3OH.[2][3][4] It is a relatively rare mineral but is found in granitic pegmatites, phosphate rock deposits, guano caves and in chondrite meteorites.[4] It was first described in 1941 and named for Herbert Percy Whitlock (1868–1948), American mineralogist and curator at the American Museum of Natural History in New York City.[3]

With regards to periodontal dentistry, magnesium whitlockite comprises one component of many of the inorganic content of calculus. It is found primarily in subgingival calculus (as opposed to supragingival calculus). It is also found more in posterior as opposed to anterior regions of the oral cavity.

  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. ^ a b Whitlockite: Whitlockite mineral data from Mindat
  3. ^ a b c Whitlockite Mineral Data from Webmineral
  4. ^ a b c http://rruff.geo.arizona.edu/doclib/hom/whitlockite.pdf Handbook of Mineralogy