Iodargyrite
- Iodargyrit
- Silver iodide and silver iodide
- Iodide
- Jodyrit
Jodargyrit, also under the various synonymous names Iodargyrit, iodide, Iodit, Iodide, Iodsilber, Jodyrit and under the chemical name silver known, is a rarely occurring mineral from the mineral class of halides. It crystallizes in the hexagonal crystal system with the chemical composition of AgI and developed mostly colorless transparent, tabular to prismatic crystals in centimeter in size, but also translucent laminar, granular to massive mineral aggregates, calling in air yellow with time. Also, pearl-gray, yellow green and brown color varieties are known.
Special Features
Before the blowpipe the mineral fuses on charcoal easily, coloring the flame red-blue and leaves a silver grain. At 146 ° C it turns into the cubic, red modification.
Etymology and history
Was first found in 1859 in the Jodargyrit " Albarradón Mine" at Albarradón ( Concepción del Oro ) in the Mexican state of Zacatecas and described by Félix Alexandre Gustave Achille Leymérie, who named the mineral after its chemical constituents iodine and silver ( argyros ).
Classification
In the now outdated but still in use 8th edition of the mineral classification by Strunz the Jodargyrit belonged to the department of "simple halides ", where he led the unnamed group formed together with Tocornalit III/A.03.
The 9th edition valid since 2001 and of the International Mineralogical Association (IMA ) used the Strunz'schen Mineral classification assigns the Jodargyrit into the already fine divided department of a "Simple halides, without H2O". This is also subdivided in accordance with the molar ratio of metal (M) to the respective connected thereto, halogen (X ), so that the mineral according to its composition in the subsection "M: X = 1: 1 and 2: 3 " can be found, where it also together with the Tocornalit now named after him " Jodargyritgruppe " with the system no. 3.AA.10 forms.
The mainly common in English-speaking classification of minerals according to Dana assigns the Jodargyrit also in the class / department of " halides ". Here he can be found as the only member of the unnamed group 09:01:05 within the sub-division of " water clear and hydrated halides with the formula AX".
Education and Locations
Jodargyrit forms as a secondary mineral by oxidation in the silver-rich deposits along with other secondary silver minerals such as acanthite, Bromargyrit and Chlorargyrite, but also cerussite and native silver as accompanying minerals.
So far Jodargyrit was detected in 135 localities. Apart from its type locality Albarradón the mineral in Mexico occurred still in the " Quebradillas Mine " on to Zacatecas. Furthermore, known to ancient archaeological sites, among others, still Chañarcillo in Chile and Guadalajara in Spain.
In the Pit " Beautiful view " in Dernbach ( Germany ) several millimeters large crystals were found occasionally. Large crystals of about a centimeter and a greenish color could be rescued from the " Pinnacles Mine" at Broken Hill ( Australia).
Crystal structure
Jodargyrit crystallizes in the hexagonal crystal system in space group P63mc ( Raumgruppen-Nr. 186) with the lattice parameters a = 4.580 Å and c = 7.494 Å and two formula units per unit cell.