| Johnbaumite | |
|---|---|
 | |
| General | |
| Category | Apatite group |
| Formula (repeating unit) | Ca5(AsO4)3OH |
| IMA symbol | Jbm[1] |
| Strunz classification | 08.BN.05 |
| Dana classification | 41.08.03.03 |
| Crystal system | Hexagonal |
| Crystal class | Dipyramidal (8/m) |
| Space group | P63/m |
| Identification | |
| Colour | Greyish white to colourless |
| Crystal habit | Anhedral grains, granular minerals without the expression of crystal shapes and massive, uniformly indistinguishable crystals forming large masses. |
| Cleavage | Distinct {1010} |
| Fracture | Irregular/Uneven |
| Tenacity | Brittle |
| Mohs scale hardness | ≈ 4.5 |
| Luster | Adamantine to greasy on fracture surfaces, vitreous on cleavage surfaces |
| Streak | White |
| Diaphaneity | Transparent |
| Density | 3.65 – 3.73 g/cm3 |
| Optical properties | Uniaxial (−) |
| Refractive index | nω = 1.687 nε = 1.684 |
| Birefringence | 0.003 |
| Pleochroism | Non-pleochroic |
| Extinction | Parallel |
| 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]
- ^ 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.
- ^ "Johnbaumite". webmineral.com. Retrieved 17 June 2022.
- ^ "Johnbaumite". Mindat.org. Retrieved 17 June 2022.
- ^ 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:
- ^ 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