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with Sphalerite, tetrahedrite, and galena. Chalcopyrite typically occurs in trace <br />amounts subordinate to the associated tellurides and native metals. <br />• Galena (PbS): Galena is only a minor accessory mineral in the telluride deposits. It is <br />usually associated with Sphalerite and tetrahedrite when it is found. <br />• Marcasite (FeS~: Mazcasite is rarely observed, and usually only in trace amounts. <br />When it is found, marcasite is commonly intergrown with pyrite. Hypogene <br />mazcasite was deposited eazly in the vein sequence and is typically veined and <br />replaced by the younger sulfides, tellurides, and native metals with which it is <br />associated. <br />• Pyrite (FeS~: Pyrite is the most abundant sulfide mineral found in the telluride veins <br />and as disseminations in the wall rock immediately adjacent to the telluride veins. It <br />is most commonly found asfine-grained disseminations in the telluride-bearing <br />quartz; either uniformly distributed throughout the quartz, or concentrated in bands or <br />zones within the quartz. It also occurs attached to the walls of vugs or seams within <br />the quartz veins and as layers coating eazly vein quartz along the borders of telluride <br />veinlets. In altered wall rock adjacent to the telluride veins, pyrite is normally very <br />fine-grained to fine-grained or found in minute seams. Pyrite also occurs in various <br />stages of replacement biotite in the wall rocks. Most of the pyrite in the telluride <br />veins formed in the eazliest stages of mineralization and is coated, veined, or replaced <br />by the numerous ore minerals that followed it in the vein sequence. <br />• Sphalerite (Zn, Fe)S: Spalerite can be present in accessory amounts in the telluride <br />veins. It formed early in the sulfide sequence and is veined and replaced by closely <br />associated chalcopyrite, tetrahedrite, and galena. Sphalerite is commonly intergrown <br />with chalcopyrite. <br />4 <br />