Cerargyrite & Embolite Composition, Crystallization & Structure

Crystallization. Isometric. Habit cubic.

Structure. Usually massive, resembling wax; often in plates and crusts.

Physical Properties. H. = 2-3. G. = 5.8.6. Sectile, can be cut with a knife like horn. Transparent to translucent. Color pearl-gray to colorless. Rapidly darkens to violet-brown on exposure to light.

Test. Very easily fusible at 1. B.B. on charcoal gives a globule of silver. Insoluble in nitric acid, but slowly soluble in ammonium hydroxide.  When heated with galena in C.T. gives a white sublimate of lead chloride. Distinguished chiefly by its horny or warlike appearance and its sociality.

Occurrence. Cerargyrite is an important secondary ore of silver. It is only to be found in the upper, enriches zone of silver veins where descending waters containing small amounts of chlorine have acted upon the oxidized products of the primary silver ores of the vein. Found associated with other silver ores, galena, etc.; with native silver, cerussite and secondary minerals in general. Was an important mineral in the mines at Leadville and elsewhere in Colorado, at the Comstock Lode in Nevada, in crystals at the Poorman’s Lode in Idaho. Notable amounts have been found in New South Wales, Peru, Chile, Bolivia, and Mexico.

Name. Cerargyrite is derived form two Greek words meaning horn and silver, in allusion to its hornlike appearance and characteristics.

Use. Silver ore.

Embolite
Composition, Ag (C1,Br). Crystallization, structure and physical properties, like those of Cerargyrite (which see). Test, same as for cerargyrite, except that, when heated in C.T. with galena, it gives a lead bromide sublimate, witch is yellow when hot and white when cold. Occurrence, same as for cerargyrite, with which it is usually found, but much rare.

Other similar silver compounds which are still rarer in their occurrence, are, bromyrite, AgBr; iodobromite, Ag (C1, Br,I); iodyrite, AgI.