Rayit
| Rayit | |
|---|---|
| General and classification | |
| other names |
IMA 1982-029 |
| chemical formula | Pb 8 (Ag, Tl) 2 Sb 8 S 21 |
|
Mineral class (and possibly department) |
Sulphides |
|
System no. to Strunz and to Dana |
2.HC.10 ( 8th edition : II / E.21) 06/03/20/05 |
| Crystallographic Data | |
| Crystal system | monoclinic |
| Crystal class ; symbol | monoclinic prismatic; 2 / m |
| Space group | C 2 / c (No. 15) |
| Lattice parameters |
a = 13.60 Å ; b = 11.96 Å; c = 24.49 Å β = 103.94 ° |
| Formula units | Z = 4 |
| Physical Properties | |
| Mohs hardness | Please complete |
| Density (g / cm 3 ) | 6.13 (calculated) |
| Cleavage | Please complete |
| colour | lead gray |
| Line color | lead gray |
| transparency | opaque |
| shine | Metallic luster |
| Crystal optics | |
| Pleochroism | greenish to greenish-blue |
Rayite is a very rare mineral from the mineral class of sulfides . It crystallizes in the monoclinic crystal system with the chemical composition Pb 8 (Ag, Tl) 2 Sb 8 S 21 and so far only known in the form of microcrystalline, granular aggregates , the individual crystallites of which reach a size of 30 μm to 0.5 mm.
Rayit is lead-gray in color and line color , but shows a white color with a greenish to bluish tinge when reflected light. Its calculated density is 6.13 g / cm³.
Etymology and history
The mineral was first described in 1983 by K. Basu, NS Bortinikov, A. Moorkhetjee, NN Mozgova, AI Tespin and LN Vyalsov, who named it Rayit in honor of Santosh Kumar Ray , an Indian professor of petrology .
classification
In the old (8th edition) and new systematics of minerals according to Strunz (9th edition) , the rayit belongs to the department of sulfosalts . The new Strunz'sche mineral systematic subdivides here more finely according to the cations involved , so that the mineral is now in the subdivision of "Sulphosalts with SnS as a model, only with lead (Pb)".
The systematics of minerals according to Dana assigns the Rayit to the “ fuloppite group (monoclinic: C2 / c contains Pb, Sb) ” of the “sulfosalts with the ratio 2.0 <z / y <2.49 and the composition (A +) ) i (A 2+ ) j [B y C z ], A = metals, B = semi-metals, C = non-metals ".
Crystal structure
Rayit crystallizes in the monoclinic crystal system in the space group C 2 / c (space group no.15 ) with the lattice parameters a = 13.60 Å , b = 11.96 Å, c = 24.49 Å and β = 103.94 °, as well as four formula units per unit cell .
Education and Locations
So far, Rayit has only been found at its type locality , in the "Rajpura Dariba deposit" (Dariba Mine) near Udaipur in India. There it occurs embedded in the kyanite - graphite - shale of polymetallic sulphide deposits from the Precambrian period and in paragenesis with galena , meneghinite and owyheeit .
See also
literature
- Rayite . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 ( handbookofmineralogy.org [PDF; 62 kB ; accessed on May 16, 2018]).
Web links
- Mineral Atlas: Rayit (Wiki)
Individual evidence
- ↑ a b c Webmineral - Rayite (English)
- ↑ a b c d e Pete J. Dunn, Joel D. Grice, Michael Fleischer, Adolf Pabst: New Mineral Names . In: American Mineralogist . tape 69 , 1984 ( rruff.info [PDF; 1000 kB ; accessed on May 16, 2018]).
- ↑ Stefan Weiß: The large Lapis mineral directory. All minerals from A - Z and their properties . 6th completely revised and supplemented edition. Weise, Munich 2014, ISBN 978-3-921656-80-8 .
- ↑ Find location list for Rayit in the Mineralienatlas and Mindat