Polhemusit
| Polhemusit | |
|---|---|
| General and classification | |
| other names |
IMA 1972-017 |
| chemical formula | (Hg, Zn) p |
|
Mineral class (and possibly department) |
Sulfides and sulfosalts |
|
System no. to Strunz and to Dana |
2.CB.05c ( 8th edition : II / C.01) 08/02/03/01 |
| Crystallographic Data | |
| Crystal system | tetragonal |
| Crystal class ; symbol | 4 / m or 4 / m 2 / m 2 / m |
| Space group | P 4 / n , P 4 2 / n , P 4 / nbm , P 4 / nmm , P 4 2 / nnm or P 4 2 / ncm |
| Lattice parameters | a = 8.71 Å ; c = 14.74 Å |
| Formula units | Z = probably between 24 and 32 |
| Physical Properties | |
| Mohs hardness | 4.5 |
| Density (g / cm 3 ) | 4.23 to 5.63 (calculated, depending on the number of formula units) |
| Cleavage | Please complete |
| colour | black |
| Line color | Please complete |
| transparency | opaque, translucent in thin areas |
| shine | resinous to diamond-like |
Polhemusite is a very rare mineral from the mineral class of sulfides and sulfosalts . It crystallizes in the tetragonal crystal system with the chemical composition (Hg, Zn) S and forms up to 25 μm large prisms or dipyramids as well as microscopic grains of black, in bare areas gray in color.
Etymology and history
The mineral was first found in 1978 by BF Leonard, George A. Desborough and Cynthia W. Mead near Big Creek , Idaho, USA . They named it after the American geologist Clyde Polhemus Ross .
classification
In the Strunz system , hawleyite is a metal sulfide with a ratio of metal to sulfur, selenium or tellurium of 1: 1. After the 8th edition , it forms the sphalerite group together with Coloradoite , Stilleit , Rudashevskyite , Hawleyite , Sphalerite , Metacinnabarite and Tiemannite . In the 9th edition it forms with these minerals and sakuraiite a subgroup of the sulfides with zinc , iron , copper or silver .
In the Dana system , it forms its own subgroup of sulfides, selenides and tellurides with the composition A m B n X p , with (m + n): p = 1: 1.
Education and Locations
Polhemusit forms in stibnite -Occurrence. It is associated with stibnite, cinnabarite , sphalerite and metacinnabarite .
In addition to its type locality , only four other sites are currently (as of June 2011) known. The mineral was found in Baojing in China , Takāb in Iran , Stazzema in Italy and Potosi in the US state of Nevada .
Crystal structure
An exact crystal structure could not be determined because the crystals were too small. The mineral crystallizes in the tetragonal crystal system with the lattice parameters a = 8.71 Å and c = 14.74 Å. As space group is P 4 / n, P 4 2 / n, P 4 / nbm, P 4 / NMM, P 4 2 / nnm or P 4 2 / ncm possible, the number of formula units per unit cell is probably between 24 and 32.
See also
Individual evidence
- ↑ a b c d e B. F. Leonard, George A. Desborough and Cynthia W. Mead: Polhemusite, a new Hg-Zn sulfide from Idaho. In: American Mineralogist. 1978, 53, pp. 1153–1161 ( full text ; PDF; 991 kB).
- ^ New Dana Classification of Sulfide Minerals
- ↑ Polhemusite at mindat.org (Engl.)
literature
- Polhemusit in: Anthony et al .: Handbook of Mineralogy , 1990, 1, 101 ( pdf ).