Proustit
| Proustit | |
|---|---|
 |
|
| General and classification | |
| other names |
|
| chemical formula | Ag 3 [AsS 3 ] |
|
Mineral class (and possibly department) |
Sulfides and sulfosalts |
|
System no. to Strunz and to Dana |
2.GA.05 ( 8th edition : II / E.07) 04/03/01/01 |
| Similar minerals | Pyrargyrite (dark red to brownish bluish line), cuprite , hematite and cinnabar |
| Crystallographic Data | |
| Crystal system | trigonal |
| Crystal class ; symbol | ditrigonal-scalenohedral 3 2 / m |
| Room group (no.) | R 3 c (No. 161) |
| Lattice parameters | a = 10.82 Å ; c = 8.69 Å |
| Formula units | Z = 6 |
| Frequent crystal faces | {01 1 2} or {10 1 1} (rhombohedral), {12 3 1} (scalenohedral) |
| Twinning | after {10 1 4} forming triplets, also possible after {10 1 1}, {0001} and {01 1 2} |
| Physical Properties | |
| Mohs hardness | 2 to 2.5 |
| Density (g / cm 3 ) | measured: 5.57; calculated: 5.625 |
| Cleavage | clearly after {10 1 1} |
| Break ; Tenacity | shell-like to uneven; brittle |
| colour | scarlet to vermilion |
| Line color | vermilion |
| transparency | translucent to opaque, rarely transparent |
| shine | Diamond luster |
| Crystal optics | |
| Refractive indices |
n ω = 3.087 to 3.088 n ε = 2.792 |
| Birefringence | δ = 0.295 to 0.296 |
| Optical character | uniaxial negative |
| Pleochroism | ε = scarlet to vermilion; ω = blood red |
Proustite , outdated including as light Rotgültigerz , ruby orifice or arsenic silver bezel known is a relatively rare occurring mineral from the mineral class of " sulfides and sulfosalts ". It crystallizes in the trigonal crystal system with the composition Ag 3 [AsS 3 ], so it is chemically seen a belonging to the sulfosalts silver - Sulfoarsenid .
Proustite usually develops translucent to opaque and often flat crystals with short to long prismatic, rhombohedral or scalenohedral habit and flat or pointed pyramidal ends. It can also be found in the form of granular to massive mineral aggregates , crusty coatings or dendrites . Visible crystal surfaces have a diamond-like sheen .
Etymology and history
The term Rotgültig or Rotgültigerz (also Rotgültigertz after Mathesius 1562), red Güldig Ertz (after Ercker 1580) and Rothgüldenerz (after Henckel 1754) was known since the 16th century, miners and became the name of rich silver - ores with reddish color and a strong, glare- like sheen. The name Rothgüldenerz has also been passed down by Johann Friedrich Henckel since 1754 .
Abraham Gottlob Werner distinguished between dark and light red gold ore as early as 1789 , but the chemist Joseph Louis Proust was only able to clarify through his chemical analyzes in 1804 that the red gold ores of antimony ( dark , Ag 3 SbS 3 ) and arsenic ( light , Ag 3 AsS 3 ) are two separate minerals.
While the more common dark red gold ore was given the name Pyrargyrit (from the Greek π 18ρ [pûr] “fire” and ἄργυρος [argyros] for “silver”) by Ernst Friedrich Glocker in 1831 , François Sulpice Beudant named the light red gold ore after Proust in 1832 Achievement to clarify the context in order to appreciate the red valid ore.
classification
In the now outdated, but still in use 8th edition of the mineral classification according to Strunz , Proustite belonged to the mineral class of "sulfides and sulfosalts" and there to the department of "sulfosalts", where together with pyrargyrite , pyrostilpnite , quadratite , samsonite and xanthocone it was an independent group II / E.07 formed.
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 the Proustite to the class of “sulfides and sulfosalts”, but in the newly defined section of “sulfoarsenides, sulfoantimonides, sulfobismuthides” " a. This department is further subdivided according to the crystal structure and the possible presence of additional sulfur , so that the mineral according to its structure and its composition in the subdivision of "island sulfarsenides (Neso sulfarsenides) etc., without additional sulfur (S)" is to be found where it only forms the unnamed group 2.GA.05 together with pyrargyrite .
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the Proustite to the class of "sulfides and sulfosalts" and there in the department of "sulfosalts". Here he is together with pyrargyrite in the "Proustitgruppe" with the system no. 03.04.01 within the subdivision " 03.04 Sulphosalts with the ratio 3> z / y and the composition (A +) i (A2 +) j [ByCz], A = metals, B = semi-metals, C = non-metals ".
Crystal structure
Proustite crystallizes trigonal in the space group R 3 c (space group no. 161) with the lattice parameters a = 10.82 Å and c = 8.69 Å as well as 6 formula units per unit cell .
The crystal structure consists of a rhombohedral unit cell, the corners and center of which are occupied by AsS 3 groups. These groups form flat pyramids with As at the tip, the Ag atoms are located in the gaps, with each S atom having two Ag atoms as closest neighbors.
properties
The color of fresh prostite samples varies between scarlet and vermilion red . When exposed to light, the mineral darkens over time and becomes almost black. At the same time it "turns gray" due to a fine silver coating. However, it can be distinguished from the very similar, also darkening pyrargyrite by its lighter, vermilion streak color .
In front of the soldering tube , Proustite melts on carbon to form a grain of silver, with an arsenic smell becoming noticeable.
Education and Locations
Proustite is formed primarily from arsenic-rich hydrothermal solutions in cobalt-nickel and lead-zinc vein deposits. Accompanying minerals can include solid silver , stephanite , rhodochrosite , galena , pyrite , argentite and pyrargyrite .
As a rather rare mineral formation, Proustite can sometimes be abundant at various sites, but overall it is not very common. So far (as of 2011) around 660 sites are known. The silver deposit near Chañarcillo in the Little North of Chile, where up to 10 cm long crystals emerged, is known for its extraordinary Proustite finds. The longest known crystal with over 12 cm was found in 1936 near Schneeberg (Saxony, Germany) and the "Poorman Mine" near Banner in Boise County (Idaho, USA) made discoveries of crystalline masses weighing over 250 kg in 1865 known.
Other locations include Argentina , Australia (New South Wales), Bolivia , Chile , China , Germany (Ore Mountains, Harz, Black Forest), Fiji (Viti Levu), France , Greece , Indonesia (Sumatra), Ireland , Italy (Sardinia) ), Japan , Canada (Ontario), Kazakhstan , Madagascar , Morocco (Souss-Massa-Daraâ), Mexico (Chihuahua, Guanajuato, Guerrero), New Zealand , Norway , Austria (Carinthia, Salzburg, Tyrol), Peru , Philippines (Luzon) , Poland (Lower Silesia), Romania , Russia , Saudi Arabia , Sweden , Switzerland (Canton Valais), Slovakia (Banská Bystrica, Košice), South Africa , Spain (Andalusia), Czech Republic (Bohemia, Moravia), Hungary (Borsod-Abaúj- Zemplén), the United Kingdom (England, Wales) and the United States (Arizona, Colorado, Idaho, Nevada).
use
As a "noble" silver ore (silver content: 65.41%), Proustite is mined for silver production.
See also
literature
- Martin Okrusch, Siegfried Matthes: Mineralogy. An introduction to special mineralogy, petrology and geology . 7th fully revised and updated edition. Springer Verlag, Berlin et al. 2005, ISBN 3-540-23812-3 , pp. 42 .
- AG Betechtin (А. Г. Бетехтин): Textbook of special mineralogy . 2nd Edition. VEB Verlag Technik, Berlin 1957, p. 232–234 (Russian: Курс минералогии . Translated by Wolfgang Oestreich).
Web links
- Mineral Atlas: Proustite (Wiki)
Individual evidence
- ↑ a b c d e Hugo Strunz , Ernest H. Nickel: Strunz Mineralogical Tables . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p. 119 .
- ↑ a b Webmineral - Proustite (English)
- ↑ a b c John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols: Proustite , in: Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 61.4 kB )
- ↑ a b c d MinDat - Proustite (English)
- ↑ a b c Paul Ramdohr , Hugo Strunz : Klockmanns textbook of mineralogy . 16th edition. Ferdinand Enke Verlag, 1978, ISBN 3-432-82986-8 , pp. 472 .
- ↑ a b F. S. Beudant : Proustite, argent antimonié sulfuré en partie , in: Traité Élémentaire de Minéralogie , 2nd Edition, Chez Verdière Libraire-Éditeur, Paris 1832, pp. 445–447 ( PDF 121.9 kB )
- ↑ a b c Hans Lüschen: The names of the stones. The mineral kingdom in the mirror of language . Ott Verlag, Thun and Munich 1968, p. 304-305 .
- ^ GeoMuseum of the Clausthal University of Technology - Pyrargyrit
- ^ Helmut Schrätze, Karl Ludwig Weiner: Minéralogie: A textbook on a systematic basis in the Google book search
- ↑ a b Petr Korbel, Milan Novák: Mineral Encyclopedia . Nebel Verlag GmbH, Eggolsheim 2002, ISBN 3-89555-076-0 , p. 50 .
- ↑ Mineral Atlas: Mineral Records
- ↑ Mindat - Localities for Proustites