Iodine argyrite
| Iodine argyrite | |
|---|---|
 |
|
| General and classification | |
| other names |
|
| chemical formula | β-AgI |
|
Mineral class (and possibly department) |
Halides |
|
System no. to Strunz and to Dana |
3.AA.10 ( 8th edition : III / A.01b) 01/09/05/01 |
| Similar minerals | Chlorargyrite and bromargyrite |
| Crystallographic Data | |
| Crystal system | hexagonal |
| Crystal class ; symbol | dihexagonal-pyramidal; 6 mm |
| Space group | P 6 3 mc (No. 186) |
| Lattice parameters | a = 4.59 Å ; c = 7.51 Å |
| Formula units | Z = 2 |
| Physical Properties | |
| Mohs hardness | 1 to 1.5 |
| Density (g / cm 3 ) | 5.5 to 5.7 |
| Cleavage | completely after {0001} |
| Break ; Tenacity | shell-like |
| colour | colorless, pearl gray, yellow green, brown |
| Line color | white, pearl gray, green to yellow-green, brown |
| transparency | transparent to translucent |
| shine | strong fat luster to diamond luster |
| Crystal optics | |
| Refractive indices |
n ω = 2.210 n ε = 2.220 |
| Birefringence | δ = 0.010 |
| Optical character | uniaxial positive |
Jodargyrite , also known under the various synonymous names iodargyrite , iodite , iodite , iodized silver , iodized silver , iodyrite and under the chemical name silver iodide , is a rather seldom occurring mineral from the mineral class of halides . It crystallizes in the hexagonal crystal system with the chemical composition β-AgI and develops mostly colorless, transparent, tabular to prismatic crystals in the size of a few centimeters, but also translucent, leafy, granular to massive mineral aggregates that turn yellow in the air over time. Pearl-gray, yellow-green and brown color varieties are also known.
Etymology and history
Iodargyrite was first found in 1859 in the "Albarradón Mine" near Albarradón (Concepción del Oro) in the Mexican state of Zacatecas and described by Alexandre Félix Gustave Achille Leymérie , who named the mineral after its chemical components iodine and silver ( argyros ).
classification
In the now outdated, but still in use 8th edition of the mineral classification according to Strunz , iodine argyrite belonged to the department of "simple halides", where it was the only member of the unnamed group III / A.01b .
The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), classifies iodine argyrite in the already more finely subdivided division of “simple halides without H 2 O”. This is further subdivided according to the molar ratio of metal (M) to the halogen (X) associated with it , so that the mineral can be found in the sub-section "M: X = 1: 1 and 2: 3" according to its composition, where, together with tocornalite, the "Jodargyritgruppe" now named after him with the system no. 3.AA.10 forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , also assigns iodine argyrite to the class / division of "halides". Here he is to be found as the only member of the unnamed group 09.01.05 within the subdivision of " Anhydrous and water-containing halides with the formula AX ".
Crystal structure
Jodargyrite crystallizes in the hexagonal crystal system in the space group P 6 3 mc (space group no.186) with the lattice parameters a = 4.59 Å and c = 7.51 Å as well as two formula units per unit cell .
properties
In front of the soldering tube, the mineral melts slightly on carbon, colors the flame red-blue and leaves behind a grain of silver. At 146 ° C it changes into the cubic, red modification .
Education and Locations
Iodine argyite is formed as a secondary mineral through oxidation in silver-rich deposits together with other secondary silver minerals such as acanthite , bromine argyite and chlorine argyrite , but also cerussite and native silver as accompanying minerals .
So far, iodine argyite has been found at 135 sites. In addition to its type locality Albarradón, the mineral occurred in Mexico in the "Quebradillas Mine" near Zacatecas . In addition, Chañarcillo in Chile and Guadalajara in Spain are still known at old sites .
Crystals several millimeters in size have sometimes been found in the “Schöne Aussicht” mine near Dernbach (Germany). Large crystals of over one centimeter and a greenish color were recovered from the “Pinnacles Mine” near Broken Hill (Australia).
See also
literature
- Jodargyrite . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 (English, handbookofmineralogy.org [PDF; 61 kB ; accessed on November 26, 2018]).
- Friedrich Klockmann : Klockmann's textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke, Stuttgart 1978, ISBN 3-432-82986-8 , pp. 486 (first edition: 1891).
- Petr Korbel, Milan Novák: Mineral Encyclopedia (= Villager Nature ). Edition Dörfler im Nebel-Verlag, Eggolsheim 2002, ISBN 978-3-89555-076-8 , p. 70 .
Web links
- Mineral Atlas: Jodargyrite (Wiki)
- American Mineralogist Crystal Structure Database - Iodargyrite (English)
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. 149 (English).
- ↑ Webmineral - Iodargyrite (English)
- ↑ a b Mindat - Iodargyrite (English)
- ↑ Mindat - Number of localities for iodargyrite
- ↑ List of locations for iodine argyite in the [Mineralienatlas] and in Mindat