Chlorargyrite

chlorargyrite

smithsonite

bayldonite

cerussite

Images

Formula: AgCl
Chloride
Specific gravity: 5.5 to 5.6
Hardness: 1½
Streak: White to grey
Colour: Colourless, white, yellowish, brownish, grey, black
Melts at 455°
Common impurities: I
Environments:

Hydrothermal environments

Chlorargyrite is a secondary mineral found in the oxidation zone of silver deposits, especially in arid regions, and in epithermal (low temperature) veins. It is found associated with native silver, cerussite and other secondary minerals.

Localities

At the Broken Hill district, Yancowinna county, New South Wales, Australia, the deposit originally formed in a shallow lake or submarine rift and now comprises an intensely granulite and upper amphibolite facies metamorphosed and deformed sequence of sedimentary and volcanic rocks, and minor iron-rich and layers. Quartz-feldspar gneiss probably originated from felsic volcanic rocks and associated granitic intrusions, while amphibolites reflect metamorphosed mafic magmas originally emplaced as flows and associated intrusions. Subaqueous hydrothermal precipitation involving ore fluids from crustal, magmatic, evaporitic, and possibly lacustrine sources produced metal-rich deposits. Prolonged oxidation and weathering of the sulphide-rich orebodies in the near-surface environment produced a zone greatly enriched in silver and lead and many attractive, well-crystallised secondary minerals. This oxidised zone has long been removed by mining; current operations access the deeper, primary sulphide-rich orebodies (R&M 97.1.16-26).
Chlorargyrite occurs in vuggy coronadite with goethite, sometimes associated with smithsonite. It is also found with cerussite, dolomite and malachite. At deeper levels it is a late-stage mineral in the arsenate zones, associated with carminite and members of the segnitite to beudantite series (AJM 3.1.34).

At the San Rafael Mine, Quartz Mountain camp, Lodi Mining District, Lodi Hills, Nye County, Nevada, USA, chlorargyrite and bromargyrite occur sparingly, associated with mimetite, anglesite and bayldonite (R&M 85.6.516).

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