Iodyrite: Properties and Occurrences

Iodyrite or iodargyrite is a natural mineral form of silver iodide. It is a yellowish or greenish hexagonal mineral AgI consisting of native silver iodide usually occurring in thin plates. It is is not radioactive. It is related to chlorargyrite and bromargyrite.

General Information:

  • Category: Halide minerals
  • Formula: AgI
  • Crystal system: Hexagonal
  • Crystal class: Dihexagonal pyramidal (6mm)

Fig: Iodyrite – a natural mineral form of silver iodide


  • Color: Colorless (fresh); pale yellow, yellow, greenish yellow, brownish, grayish
  • Mohs scale hardness: 1.5 – 2
  • Luster: Adamantine, resinous
  • Streak: Yellow (shining)
  • Diaphaneity: Transparent, translucent
  • Specific gravity: 5.69
  • Optical properties: Uniaxial (+)


It is a mineral, AgI, that is a naturally occurring form of silver iodide, is yellowish or greenish in color, is found in parts of Central and South America, and is hexagonal in shape


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