Iodargyrite
Composition: AgI
Crystal System: Hexagonal
Color: Colorless when fresh, darkening to sulfur yellow, brownish, greenish
Type Locality: Albarradon Mine, Conception del Oro, Zacatecas, Mexico
Iodargyrite is one of the rarest minerals containing silver, and is one of the few known minerals that contain the element iodine. The mineral is named for its composition: Iod for iodine and argyrite after the Greek argyros, meaning silver. It is found in the oxidized zone of silver deposits in arid climates. Coloration of the mineral is usually bright sulfur yellow and rarely greenish or brown.
In Nevada, iodargyrite was found in quantity in several mines around Tonopah, Nye County. There, it occurred in the oxidized portions of the silver veins as single crystals and groups, sometimes twinned. Crystals rarely reached more than five millimeters in length. In the Mizpah Mine, iodargyrite was common enough to be considered an ore of silver, and it was very rich ore as the mineral contains 46% silver by weight.
Worldwide, iodargyrite is very rare, with large amounts found at only two other localities: Broken Hill, New South Wales, Australia, and Chanarcillo, Chile. In both of those locations the silver ore has been worked out.
 Iodargyite - specimen is 2.0 mm. Photo by Ben Schumer |
 Iodargyrite on gypsum. Specimen in 2.5 cm. Photo by Ben Schumer |
 UNR
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