Argentite
| Argentite | |
|---|---|
 |
|
| General and classification | |
| chemical formula | Ag 2 S |
|
Mineral class (and possibly department) |
Sulphides and sulphosalts - metal: sulfur (selenium, tellurium)> 1: 1 |
|
System no. to Strunz and to Dana |
2.BA.30a ( 8th edition : not awarded) 02.00.00.00 |
| Similar minerals | Acanthite |
| Crystallographic Data | |
| Crystal system | cubic |
| Crystal class ; symbol | cubic hexakisoctahedral; 4 / m 3 2 / m |
| Space group | In 3 m (No. 229) |
| Lattice parameters | a = 4.89 Å |
| Formula units | Z = 2 |
| Physical Properties | |
| Mohs hardness | 2 to 2.5 |
| Density (g / cm 3 ) | 7.1 |
| Cleavage | indistinct after {001} and {110} |
| Break ; Tenacity | uneven |
| colour | black, gray |
| Line color | lead gray |
| transparency | opaque |
| shine | Metallic luster |
Argentite (outdated silver luster ) is a previously hypothetical but not recognized mineral from the mineral class of " sulfides and sulfosalts ", which as a high-temperature modification of silver sulfide (Ag 2 S) is only stable up to a temperature of 173 ° C.
Argentite initially crystallizes in the cubic crystal system , but then transforms into monoclinic acanthite as it cools down, whereby it mostly retains the external crystal form of argentite. These paramorphoses are often incorrectly and misleadingly referred to as "argentite" due to ignorance of the exact facts. Correctly, they should either be called "pseudomorphoses from acanthite to argentite" or "pseudocubic acanthite".
Etymology and history
Argentite was first scientifically described in 1845 by Wilhelm Ritter von Haidinger , who named the mineral after the Latin word argentum for silver.
classification
In the 9th edition of the Strunz mineral classification, argentite is classified together with acanthite.
The systematics of minerals according to Dana does not classify the argentite more precisely, it has the system number 2.00.00.00 here
Crystal structure
Argentite crystallizes cubically in the space group Im 3 m (space group no. 229) with the lattice parameter a = 4.89 Å and 2 formula units per unit cell .
Education and Locations
Argentit forms only temporarily in high grade hydrothermal solutions of over 173 ° C in silver ore - courses . Below this temperature, acanthite forms directly as a stable phase. Paragenesis and sites see acanthite .
use
Along with acanthite, argentite is one of the most important raw materials for the extraction of silver .
See also
literature
- Martin Okrusch, Siegfried Matthes: Mineralogy: An introduction to special mineralogy, petrology and deposit science . 7th edition. Springer Verlag, Berlin, Heidelberg, New York 2005, ISBN 3-540-23812-3 , pp. 32 (argentite and acanthite) .
- Petr Korbel, Milan Novák: Encyclopedia of Minerals . Nebel Verlag GmbH, Eggolsheim 2002, ISBN 3-89555-076-0 , p. 23 .
- Paul Ramdohr , Hugo Strunz : Klockmann's textbook of mineralogy . 16th edition. Ferdinand Enke Verlag, 1978, ISBN 3-432-82986-8 , pp. 421-422 .
Web links
- Mineral Atlas: Argentite (Wiki)
- Mindat - Argentite (English)
Individual evidence
- ↑ a b Webmineral - Argentite (English)
- ↑ IMA / CNMNC List of Mineral Names - Argentite (English, PDF 1.8 MB; p. 16)