Silver Bearing Minerals

Man has used this metal for centuries. It sometimes is found in native silver, but is more commonly foimd combined with sulfur as argentenite. Most of the World s supply of silver is obtained as a by-product when other metals such as lead, zinc, and copper are processed. Silver is used in photography, in medicines, and in coins. 

Natural silver halogenides, which are secondary ores for silver production, are characterized by intensive luminescence under powerful laser excitation (Fig. 4.67). The main source of the backgroimd liuninescence is the sorption of organic matter. The relatively long decay time of their liuninescence may enable us to lower the short-lived background emission by several orders of magnitude. 

Native silver and argentenite are not luminescent in their natural form, but as in the case of gold, it is possible to induce the artificial emission (Fig. 8.19). 

Silver has many intensive lines in the breakdown spectrum, the strongest ones at 328 and 338 nm in the UV part of the spectrum and at 520 and 546 nm in the visible (Fig, 8.21), which it may be potentially used in radiometric sorting. Silver is relatively uniformly distributed in massive sulfide ores (average values for the deposits 10-50 ppm), but local enrichments occur (up to 150-300 ppm of Ag) (Prokin et al. 1999). 

---

Almeida, M. F. Amarante, M. A. Leaching of a silver-bearing sulfide by-product with cyanide thiourea and chloride solutions. Miner. Eng. 1995, 8, 257-271. 

Freibergite is the dominant host for Ag in the HRMZ, wherein Ag concentrations increase stratigraphically upwards with 99% of Ag hosted by type 5 mineralization (Table 1). Silver-bearing chalcopyrite contains 40% of the Ag in type 2a mineralization and 13% in type 3 where chalcopyrite contains up to 7.29 wt.%. Within both freibergite and chalcopyrite, Ag directly substitutes for Cu in the mineral lattice. Freibergite within the HRMZ is also consistently enriched in Ag (21.9 to 38.5%) compared to many other VMS deposits (e.g. Kidd Creek Hannington et al. 1999, Heath Steele Chen Petruk 1980, Rosebery Huston et al. 1996). 

Fig. 8.19. Artificially induced luminescence on Au (upper) and Ag bearing minerals (1 - silver and argentenite 2 - galenite) (Gaft et al. 1989c)...

The mineral galena is the primary source of lead or Saturn. The alchemieal importanee of galena is that it is auriferous (bears gold) and produees eonsiderable amounts of antimony when it is refined. Other impurities inelude eopper, zine, silver, arsenic and selenium. 

---