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.