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SPURR MONOGRAPH oxidized zinc ore; two large bodies, in the 3rd and 4th levels and at the Smuggler shaft open cut and the 40-ft. level in the shaft, were probably originally one, now separated [offset] by the Clark fault. Summary of Mollie Gibson and Smuggler geology, pp. 187- 188. "These two mines are distinguished from the rest of the camp in the possession of peculiar ore shoots, which are characterized by flesh-colored barite, poverty in lead [emphasis added], and by a large amount of polybasite and native silver." Major deposits lie along the east-west faults of the Della system, along fracture zones formed after Della faulting but before ore deposition. Lower grade ore is evidently replacement or impregnation of the dolomite; after deposition of low-grade ore, but before ore deposition stopped, the east-west fracture zones were formed, and fresh solutions deposited the polybasite and barite. Native silver is probably the result of polybasite alteration. After all ore deposition another fault developed nearly parallel to the Silver fault but slightly steeper, throwing rocks on the north side down and to the north dividing the orebodies and offsetting the Della system faults [Clark fault]. Summary of Smuggler mountain Geology, pp. 198-199 Geochemistry of Aspen district ore deposits, pp. 206- 242. "Near the surface the ores of the Aspen district occur as oxides, sulphates, and carbonates, mixed with sulphides, from which they evidently derived." Sulfides become dominant, then exclusive, with depth, the most common being argentiferous (silver-bearing) galena. There is much polybasite in the Smuggler and Mollie Gibson ores, generally in flesh-colored barite (p. 224). Analyses from Mollie Gibson, p. 225. Two analyses from the Mollie Gibson give 59.73$ and 56.90$ silver, with no lead. Along water courses polybasite is reduced to native silver, probably assisted by organic material in the Weber [Belden] shales. Gangue minerals, pp. 225-226. The principal gangue minerals are calcite, quartz, dolomite and barite. Paragenesis, pp. 227-229. Along veins, ferriferous dolomite, quartz, and barite appear to have crystallized simultaneously, followed very quickly but separately by sulfides (indicated by the presence of thick barite Bruce A veins that are essentially barren, and the appearance of the Mollie Gibson and Smuggler ores where silver minerals are clearly deposited between and around barite Collins - 5 - BSSLIOGRAPHY