Chemistry:Johnbaumite
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| Johnbaumite | |
|---|---|
 | |
| General | |
| Category | Apatite group |
| Formula (repeating unit) | Ca5(AsO4)3OH |
| 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 |
| |re|er}} | 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 | [1] [2] |
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]
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
- ↑ "Johnbaumite". http://webmineral.com/data/Johnbaumite.shtml.
- ↑ "Johnbaumite". https://www.mindat.org/min-2105.html.
- ↑ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine 85 (3): 291–320. doi:10.1180/mgm.2021.43. Bibcode: 2021MinM...85..291W.
- ↑ 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
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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