Pottsite
| Pottsite | |
|---|---|
 |
|
| General and classification | |
| other names |
IMA 1986-045 |
| chemical formula | PbBiH [VO 4 ] 2 • 2H 2 O |
|
Mineral class (and possibly department) |
Phosphates, arsenates and vanadates |
|
System no. to Strunz and to Dana |
8.CG.25 ( 8th edition : VII / C.32) 01/40/04/01 |
| Crystallographic Data | |
| Crystal system | tetragonal |
| Crystal class ; symbol | tetragonal-trapezoidal; 422 |
| Space group | I 4 1 22 (No. 98) |
| Lattice parameters | a = 11.08 Å ; c = 12.63 Å |
| Formula units | Z = 10 |
| Frequent crystal faces | {101}, {110}, {103}, {211} |
| Twinning | not observed |
| Physical Properties | |
| Mohs hardness | 3.5 |
| Density (g / cm 3 ) | measured: ≈ 7.0; calculated: 7.31 |
| Cleavage | not observed |
| Break ; Tenacity | brittle |
| colour | yellow |
| Line color | light yellow |
| transparency | translucent |
| shine | Diamond luster |
| Crystal optics | |
| Refractive indices |
n ω = 2.400 n ε = 2.300 |
| Birefringence | δ = 0.100 |
| Optical character | uniaxial negative |
Pottsite is a very rare mineral from the mineral class of "phosphates, arsenates and vanadates" with the chemical composition PbBiH [VO 4 ] 2 · 2H 2 O and is therefore a water-containing lead - bismuth - hydrogen - vanadate .
Pottsite crystallizes in the tetragonal crystal system , but develops only small, prismatic or dipyramidal crystals up to about one millimeter in length with a diamond-like sheen on the surfaces. The translucent crystals are bright yellow in color, but only leave a pale yellow line on the marking board . In thin layers, pottsite appears in a cloudy yellow and can then easily be confused with nadorite or, as a fine-grained aggregate , with cervantite .
Etymology and history
Pottsite was first discovered in the molybdenum, bismuth, tungsten and vanadium open-cast and underground mining "Linka" ( Linka Mine for short ) northwest of today's ghost town of Potts and near Spencer Hot Springs in Lander County of the US state Nevada and described 1988 by SA Williams, who named the mineral after its type locality .
The type material of the mineral is kept in the Natural History Museum in London (England).
classification
Already in the outdated, but partly still in use 8th edition of the mineral classification according to Strunz , the pottsite belonged to the mineral class of "phosphates, arsenates and vanadates" and there to the department of "water-containing phosphates without foreign anions ", where it was the only member of the unnamed group VII / C.32 .
The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), also assigns pottsite to the category of “phosphates etc. without additional anions; with H 2 O “. However, this is further subdivided according to the relative size of the cations involved and the molar ratio of the phosphate, arsenate or vanadate complex (RO 4 ) to the water of crystallization content , so that the mineral is classified according to its composition in the sub-section “With large and medium-sized cations; RO 4 : H 2 O = 1: 1 “can be found where it is the only member of the unnamed group 8.CG.25 .
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns pottsite to the class of "phosphates, arsenates and vanadates" and there in the department of "water-containing phosphates etc.". Here he is to be found as the only member of the unnamed group 01/40/04 within the sub-section “ Water-containing phosphates etc., with A 2+ B 2+ (XO 4 ) × x (H 2 O) ”.
Crystal structure
Pottsite crystallizes tetragonally in the space group I 4 1 22 (space group no. 98) with the lattice parameters a = 11.08 Å and c = 12.63 Å and 10 formula units per unit cell .
properties
In cold, 16% hydrochloric acid (HCl), pottsite turns lime white quickly, but does not dissolve. Cold, 20% potassium hydroxide (KOH) does not affect the mineral at all. In contrast, it dissolves easily in cold 15% nitric acid (HNO 3 ).
Education and Locations
Pottsite forms in the oxidation zone of tungsten-containing tactites , that is, in rock zones with a complex structure created by contact metamorphosis . At its Linka Mine type locality, the mineral occurred in paragenesis with bismutite , clinobisvanite , scheelite and vanadinite , but it can also be associated with cerussite , duhamelite and junoite in other localities .
Pottsite is one of the very rare mineral formations, of which only a few samples exist that have been collected at five known sites so far (as of 2014). In the USA, apart from the Linka Mine, the mineral was only found in an unnamed prospect in the Chalk Mountain District in Churchill County of Nevada.
In Germany, pottsite is known from the Krennbruch, a granite and pegmatite quarry near Matzersdorf in the Saldenburg community (Freyung-Grafenau district) and from the Ernst & Kubischek quarries near Grub in the Rinchnach community (Regen district) in Lower Bavaria.
The only other previously known site is the Las Tapias mine on Cerro Achala near Las Tapias in the Argentine province of Córdoba .
See also
literature
- SA Williams: Pottsite, a new vanadate from Lander County, Nevada . In: Mineralogical Magazine . tape 52 , 1988, pp. 389–390 ( minersoc.org [PDF; 131 kB ; accessed on December 31, 2016]).
- John Leslie Jambor , Jacek Puziewicz: New Mineral Names. Pot site . In: American Mineralogist . tape 74 , 1989, pp. 500–505 ( minsocam.org [PDF; 743 kB ; accessed on December 31, 2016]).
Web links
Individual evidence
- ↑ a b c d Hugo Strunz , Ernest H. Nickel : Strunz Mineralogical Tables. Chemical-structural Mineral Classification System . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p. 485 .
- ↑ a b c Pottsite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 63.4 kB )
- ^ A b c d e SA Williams: Pottsite, a new vanadate from Lander County, Nevada . In: Mineralogical Magazine . tape 52 , 1988, pp. 389–390 ( minersoc.org [PDF; 131 kB ; accessed on December 31, 2016]).
- ↑ a b c Mindat - Pottsite
- ↑ micro.magnet.fsu.edu - Polarized Light Microscopy Digital Image Gallery: Tactite Skarn
- ↑ a b c List of localities for Pottsite in the Mineralienatlas and Mindat