Johnbaumite

Johnbaumite is a calcium arsenate hydroxide mineral. It was first described in 1980, where it appeared in Franklin Township, Somerset County, New Jersey.[4] Johnbaumite was discovered at Harstigen mine in Sweden in the 19th century, but it was described as svabite.[5]

Johnbaumite
General
CategoryApatite group
Formula
(repeating unit)
Ca5(AsO4)3OH
IMA symbolJbm[1]
Strunz classification08.BN.05
Dana classification41.08.03.03
Crystal systemHexagonal
Crystal classDipyramidal (8/m)
Space groupP63/m
Identification
ColourGreyish white to colourless
Crystal habitAnhedral grains, granular minerals without the expression of crystal shapes and massive, uniformly indistinguishable crystals forming large masses.
CleavageDistinct {1010}
FractureIrregular/Uneven
TenacityBrittle
Mohs scale hardness≈ 4.5
LusterAdamantine to greasy on fracture surfaces, vitreous on cleavage surfaces
StreakWhite
DiaphaneityTransparent
Density3.65 - 3.73 g/cm3
Optical propertiesUniaxial (-)
Refractive indexnω = 1.687 nε = 1.684
Birefringence0.003
PleochroismNon-pleochroic
ExtinctionParallel
References[2] [3]

Etymology

It is named after geologist John Leach Baum (March 15, 1916 – October 16, 2011), who found the original specimen in 1944. He was a significant contributor to the geology and mineralogy of the Franklin deposit, and the Curator Emeritus at the Franklin Mineral Museum.

See also

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. "Johnbaumite". webmineral.com. Retrieved 17 June 2022.
  3. "Johnbaumite". Mindat.org. Retrieved 17 June 2022.
  4. Pete J. Dunn, Donald R. Peacor, Nancy Newberry; Johnbaumite, a new member of the apatite group from Franklin, New Jersey. American Mineralogist 1980;; 65 (11-12): 1143–1145. doi:
  5. Cristian Biagioni, Marco Pasero; The crystal structure of johnbaumite, Ca5(AsO4)3OH, the arsenate analogue of hydroxylapatite. American Mineralogist 2013;; 98 (8-9): 1580–1584. doi: https://doi.org/10.2138/am.2013.4443

Further reading

  • Biagioni C, Bosi F, Hålenius U, Pasero M (2017) The crystal structure of turneaureite, Ca5(AsO4)3Cl, the arsenate analog of chlorapatite, and its relationships with the arsenate apatites johnbaumite and svabite, American Mineralogist, 102, 1981-1986
  • Lee Y J, Stephens P W, Tang Y, Li W, Phillips B L, Parise J B, Reeder R J (2009) Arsenate substitution in hydroxylapatite: Structural characterization of the Ca5(PxAs1-xO4)3OH solid solution, American Mineralogist, 94, 666-675
  • Zheng Y, Gao T, Gong Y, Ma S, Yang M, Chen P (2015) Electronic, vibrational and thermodynamic properties of Ca10(AsO4)6(OH)2: first principles study, The European Physical Journal of Applied Physics, 72, 1-7
  • Anthony J W, Bideaux R A, Bladh K W, and Nichols M C (1990) Handbook of Mineralogy, Mineral Data Publishing, Tucson Arizona, USA, by permission of the Mineralogical Society of America.
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