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Author: Admin | 2025-04-28
Suitable for replacement are more abundant. These bodies form mantos spreading out from fractures and sheeted zones under impermeable covers such as porphyry sills. The replacement ores consist primarily of sphalerite and galena with appreciable silver, all in a gangue of manganosiderite with quartz and barite. The most abundant sulfide was pyrite, its deposition beginning before and ending after the formation of sphalerite and galena. Only very small amounts of gold and silver are found in this ore; but considerable amounts of a different assemblage occur irregularly throughout the replacement bodies. This assemblage consists of chalcopyrite (most abundant), hessite (Ag2Te), altaite (PbTe), argentite, gold, and a peculiar silver-bismuth-rich variety of galena which is consistently near Pb11Ag11Bi11S15 in composition.Principal faults and areas of principal ore bodies at Leadville. Dot-pattern: Pliocene and Pleistocene deposits. Hachured line: top of basement (Tweto, 1968).Replacement bodies occur all over the district, but those in the outlying areas tend to be smaller and simpler in their mineralogy.Deposition in the Leadville area as a whole spans a range of temperatures and pressures. The magnetite-hematite ores are most certainly hypothermal; the high-grade replacement bodies appear to be mesothermal; the so-called bismuth-stage assemblage is a typical leptothermal suite; and deposits in the more distant areas are clearly telethermal.Thompson et al. (1984) provides the most recent discussion of hydrothermal ore genesis at Leadville. However, DeVoto (1984) proposes some alternative concepts by theorizing that pre-existing karst (cavernous) topography within the limestone units controlled ore deposition in a manner similar to that associated with Mississippi Valley-type lead deposits.About Some of The MinesConsidering that the Leadville area encompasses nearly 2000 mines, it would be impractical to discuss them all here. The following discussion touches upon some of the more interesting claims, with the understanding that there are many more stories left untold.PRINTER BOY HILLPrinter Boy Hill Printer Boy Hill lies at the southernmost extension of the so-called Leadville gold belt. In this area gold mineralization seems to be closely related to bismuth mineralization (Loughlin and Behre, 1934, 1937). Both sulfide replacement and vein deposits occur in the area.Printer Boy MineLocating specific information on many
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