Iodargyrite

Iodyrite or iodargyrite is a natural mineral form of silver iodide.

Iodargyrite
Iodargyrite on gossan, Broken Hill Ore Deposit, New South Wales, Australia.
General
CategoryHalide minerals
Formula
(repeating unit)
AgI
Strunz classification3.AA.10
Crystal systemHexagonal
Crystal classDihexagonal pyramidal (6mm)
H-M symbol: (6mm)
Space groupP6mm
Unit cella = 4.59, c = 7.51 [Å]; Z = 2
Identification
ColorColorless (fresh); pale yellow, yellow, greenish yellow, brownish, grayish
Mohs scale hardness1 12 - 2
LusterAdamantine, resinous
StreakYellow (shining)
DiaphaneityTransparent, translucent
Specific gravity5.69
Optical propertiesUniaxial (+)
Refractive indexnω = 2.210 nε = 2.220
Birefringenceδ = 0.010

Hardness is 1.5 to 2.

Related are chlorargyrite and bromargyrite.

References

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