Johnbaumite

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]

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]

  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