Iodargyrite - Encyclopedia
Class : Halides
Subclass : Iodides
Crystal system : Hexagonal
Chemistry : AgI
Rarity : Rare
Iodargyrite (or iodyrite) is a rare silver halide, found in the superficial oxidation zones of silver and silver-bearing galena deposits. It is associated with other silver halides (chlorargyrite, bromargyrite) and with various secondary minerals of iron, lead, silver or zinc, depending on the metals present in the deposit. Its name is linked to its chemical composition. It is a pale yellow to straw yellow mineral, with strong luster, photosensitive, low hardness (1.5 to 2). The crystals are hexagonal prismatic to tabular, or barrel-shaped, usually hemimorphic ; they frequently constitute aggregates in rosettes, parallel groups or globules.
Main photo : Iodargyrite from Broken Hill, Australia © Eugene & Sharon Cisneros
Iodargyrite in the World
Twinning
A twin is known on {30-34} and can be fourlings. Paramorph of iodargyrite after miersite show repeated twinning parallel to {111} of the original miersite.
Fakes and treatments
No fakes recorded for this mineral species.
Hardness : 1.5 to 2
Density : 5.69
Fracture : Conchoidal
Streak : Yellow
TP : Translucent to transparent
RI : 2.210 to 2.220
Birefringence : 0.010
Optical character : Uniaxial +
Pleochroism : None
Fluorescence : None
Solubility : Nitric acid, sulfuric acid
Magnetism : NoneRadioactivity : None