Global InformationChaoite information
| Chaoite | |
|---|---|
| General | |
| Category | Native element mineral |
| Formula (repeating unit) | C |
| IMA symbol | Ch[1] |
| Strunz classification | 1.CB.05b |
| Crystal system | Hexagonal |
| Crystal class | Dihexagonal dipyramidal (6/mmm) H-M symbol: (6/m 2/m 2/m) |
| Space group | P6/mmm |
| Unit cell | a = 8.948 Å, c = 14.078 Å; Z = 168 |
| Identification | |
| Colour | Black |
| Crystal habit | Thin 3-15 μm intergrowth lamallae with graphite |
| Mohs scale hardness | 1 - 2 |
| Lustre | Submetallic |
| Diaphaneity | Opaque |
| Specific gravity | 3.43 (calculated) |
| References | [2][3][4] |
Chaoite, or white carbon, is a mineral described as an allotrope of carbon whose existence is disputed. It was discovered in shock-fused graphite gneiss from the Ries crater in Bavaria. It has been described as slightly harder than graphite, with a reflection colour of grey to white.[5] From its electron diffraction pattern, the mineral has been considered to have a carbyne structure,[6] the linear acetylenic carbon allotrope of carbon. A later report has called this identification, and the very existence of carbyne phases, into question, arguing that the new reflections in the diffraction pattern are due to clay impurities.[7]
- ^ 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.
- ^ Handbook of Mineralogy
- ^ Chaoite on Mindat.org
- ^ Chaoite on Webmineral
- ^ A. El Goresy, G. Donnay, A new allotriomorphic form of carbon from the Ries Crater, Science, 1969, 161, 363–364
- ^ A.G. Whittaker, P.L. Kintner, Carbon: observation on the new allotropic form, Science 1969, 165, 589
- ^ P.P.K. Smith, P.R. Buseck, Carbyne forms of carbon: do they exist? Science, 1982, 216, 984–986