Silver, sulfosalts

Mineralization was represented by quartz-chlorite-carbonate-sulfide veins with visible chalcopyrite, galena, sphalerite, pyrrhotite, cobaltite, limonite and malachite. Fractures filled by veins are identified on aerial photos as one submeridional zone up to 20 m thick and 500 m long. The northeastern linear system represented by a shear zone containing veinlets with arsenopyrite, bismuthine, gold and silver sulfosalts. Twelve veins that differ in extent and intensity of mineralization were discovered, with some veins yielding 3 wt. % Sn, 3 wt. % Cu, and up to 250 g/t Ag. 

Mexico, the leading silver producer, obtains about half of its output from mines in which silver is the principal ore metal. Many of the mines are epithermal fissure veins, and most host a polymetallic assemblage whose exploitation is economically dependent on the high silver values. Although acanthite [Ag2S] and native silver predominate in some veins, in others much of the silver occurs in silver sulfosalts and as silver substitutions in tetrahedrite [(Cu,Fe,Ag)i2Sb4Si3] and other minerals. 

Zhang S, Meyer B, Moh GH, Scholz F (1995) Development of analytical procedures based on abrasive stripping coulometry and voltammetry for solid state phase microanalysis of natural and synthetic tin-, arsenic-, and antimony-bearing sulfosalts and sulfides of thalhum, tin, lead, and silver. Electroanalysis 7 319-328. 

Glaucodot [Named from the Greek, aucos, blue, in reference to its use in the dark blue glass called smalt) (Co,Fe)AsS M= 165.15 8.45% Fe 26.76% Co 45.37% As 19.42% S (Sulfides and sulfosalts) Orthorhombic a =663 pm b = 2833 pm c= 563 pm (2=24) P.a TJmTJmTJm S.G. Cmmm Biaxial ( ) ft s 52.5% 5 (HV 1071- 1166) 5900- 6100 (6220) Habit prismatic crystals often twinned. Colon silver- to gray-white. Luster metallic. Diaphaneity opaque. Cleav e (010) perfect. Fracture brittle, uneven. Streak black. Occurrence hi -ten erature sulfide vein deposits. 1... 

Niccolite (syn., nickeline) [Named from the old German, nickel, meaning an ore which is not useful ] (ICSD 31062 and PDF 47-1737) NiAs M= 133.61159 43.92 wt.% Ni 56.08 wt.% As Traces of Fe> S, Co,Sb, Bi,and Cu (Sulfides and sulfosalts) Coordinence Ni(6) Hesigonal a = 360.9 pm c= 501.9 pm B8 hP4 (2=2) S.G. P6,/mmc P.G. 622 Niccolite type Uniaxial R = 52.0-58.3% 5-5.5 (HV 308- 455) 7780 Habit massive, reniform, columnar. Color dark tarnish red or pale copper red. Luster metallic. Diaphandty opaque. Streak brownish black. Geavage 1010 imperfect, 0001 imperfect Fracture uneven, brittle Chemical dissolved by aqua regia. Electrical resistivity 0.1 to 2 mQ.cm. Occurrence in ore veins with silver, copper, and nickel arsenides and sultides. 

Stephanite (syn., Brittle Silver Ore) [Named after the Austrian engineer, A. Stephan] (ICSD 16987 and PDF 11-108) Ag.SbS. M = 789.355 68.33 wt.% Ag 15.42 wt.%Sb 16.25 wt.% S (Sulfides and sulfosalts) Orthorhombic P.G. mm2 Biaxial 6250 L Habit pseudo hexagonal, tabular, massive. Color iron black. Diaphaneity opaque. Luster metallic. Streak black. Fracture subconchoidal. Cleavage [010] imperfect, [021] poor. 1... 

Sylvanite [Named after Transylvania] (ICSD 30874 and PDF 9-477) (Au,Ag)jTe (Sulfides and Sulfosalts) Monoclinic a s 896 pm b = 449 pm cs 1462 pm (Zs 4) P.G. 2/m Biaxial R = 48.0-60.0% 1.5-2 (HV 102- 125) 7900- 8300 Habit prismatic, skeletal, platy. Color yellowish silver white or white. Luster metallic. Diaphaneity opaque. Str steel gray. Gleavage [010] perfect. Fracture uneven. 

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