Chlorargyrite

Chlorargyrite
General
Category Halide
Formula
(repeating unit)		 AgCl
Strunz classification 3.AA.15
Crystal system Isometric
Crystal class Hexoctahedral (m3m)
H-M symbol (4/m 3 2/m)
Space group Fm3m
Identification
Color Colorless when fresh; alters to bright chartreuse-green, light yellow, light green, grey, violet-brown on exposure to light
Crystal habit Massive to columnar
Fracture Irregular/uneven, sub-conchoidal
Tenacity Sectile
Mohs scale hardness 1.5 - 2.5
Luster Adamantine, resinous, waxy
Streak White
Specific gravity 5.556
Optical properties Isotropic
Refractive index n = 2.071
References [1][2][3]

Chlorargyrite is the mineral form of silver chloride (AgCl).[4] Chlorargyrite occurs as a secondary mineral phase in the oxidation of silver mineral deposits. It crystallizes in the isometric - hexoctahedral crystal class. Typically massive to columnar in occurrence it also has been found as colorless to variably yellow cubic crystals. The color changes to brown or purple on exposure to light. It is quite soft with a Mohs hardness of 1 to 2 and dense with a specific gravity of 5.55. It is also known as cerargyrite and, when weathered by desert air, as horn silver. Bromian chlorargyrite (or embolite) is also common. Chlorargyrite is water-insoluble.

It occurs associated with native silver, cerussite, iodargyrite, atacamite, malachite, jarosite and various iron–manganese oxides.[2]

It was first described in 1875 for occurrences in the Broken Hill district, New South Wales, Australia. The name is from the Greek, chloros for "pale green" and Latin for silver, argentum.[3]

See also

References

  1. ↑ Chlorargyrite data on Mindat.org
  2. 1 2 Handbook of Mineralogy
  3. 1 2 Chlorargyrite data on Webmineral
  4. ↑ Wikisource Chisholm, Hugh, ed. (1911). "Cerargyrite". Encyclopædia Britannica (11th ed.). Cambridge University Press.
  • Palache, C., H. Berman, and C. Frondel (1951) Dana’s system of mineralogy, (7th edition), v. II, pp. 11–15
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