This guidebook provides copies of the key previously published papers of Climax, Henderson and Leadville districts. This is a departure from the traditional SEG. Guidebook format in that it does not contain new papers of the deposits. The Climax and Henderson porphyry Mo and Leadville district carbonate-hosted manto deposits are within the Colorado Mineral Belt, a mineralized belt that contains the mostproductive porphyry molybdenum and some of the largest base- and precious-metal manto deposits in the world. Since the discovery of molybdenum-bearing stockwork veinlets at Climax in 1879, the Urad orebody in 1914, and Henderson in 1964, collectively these mines have produced over 2.9 billion pounds of Mo. In late 2009, Henderson produced its billionth pound of molybdenum and in 2012 Climax commissioned a new concentrator and is now producing ore from an open pit. Significant published reserves remain and for both Climax and Henderson that total 1 billion pounds of molybdenum metal. The Leadville district is noted for its long history of production having produced 3.1 million ounces of gold, 260 million ounces of silver and significant base metals since its discovery in 1860, research on carbonate-hosted Ag-Zn-Pb-(Au) deposits, and the founding of the Guggenheim mining fortune, including the formation of ASARCO, Inc.

The low-temperature epigenetic and stratabound Pb-Zn-Cu-Ba-F-Sr–bearing ore deposits enclosed within sedimentary columns historically have been major sources of metals. Exploration companies still find these deposits to be a profitable exploration target due to their simple mineralogy as well as the large tonnage that can present, always considering the mineral districts as a whole. In northeastern México, several nonmagmatic, low-temperature Pb-Zn-F-Ba deposits have been systematically considered as magmatic-related (skarns, high-temperature replacement deposits, epithermal deposits, etc.). Recently, these deposits have been restudied and placed within a scenario of deep fluid circulation of basinal brines through the Mesozoic sedimentary series, enriched in Ba, F, and metals during fluid flow and water-rock interactions. These fluids gave rise to a series of strata-bound epigenetic ore deposits scattered throughout the whole Mesozoic carbonate platform and can be shown to be unrelated to any period of magmatism. There is no intense alteration to the host rocks. Commonly there is a close association with organic matter, either liquid hydrocarbons or bitumen; they have a very simple mineralogy of barite, celestine, fluorite, sphalerite, galena, and have low formation temperatures (90–105 °C) combined with variable salinities. These characteristics make these deposits similar to the Mississippi Valley–type deposits, possibly most similar to the Alpine-Appalachian subtype.