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Wildcat Mining Corporation Page 26 Eckel (1949) in contrast, argues convincingly that the main movement on the May Day and Idaho faults took place before mineralization and that it was nearly contemporaneous with porphyry intrusion and deformation associated with the La Plata dome. The porphyry intrusion followed the Idaho fault, but was subsequently broken by later fault motion. By this interpretation, mineralizing fluids rose along the deep fault planes, in places focused by the tight gouge dams at the faulted porphyry contacts, and deposited ore in the open fractures and reactive rock on both sides of the principal fault zones. If this model is in fact true, Eckel recognized the possibility that ore veins may be more extensive than now apparent and that unrecognized segments of any or all of the veins remain to be discovered. He suggested that failure to discover these segments may have been due to the fact that several of the development drifts follow fault gouge zones so closely that they could have missed a vein in the adjacent competent sedimentary rock. Evidence to definitively test the two models did not exist in 1949 and has not been gathered subsequently. Prudent future exploration should consider both hypotheses as potentially valid. DEPOSIT TYPES The La Plata Mountains contain a variety of metallic ore deposit types, including • porphyry Cu -Au deposits in syenite, Au -Cu skarn and contact breccia deposits, pyritic Au vein and replacement deposits, Ag -Au bearing polymetallic vein and replacement deposits and ruby silver vein deposits. Mutschler and others (1998) have highlighted the probable genetic association of these deposits with the suite of igneous intrusive rocks of distinctively alkaline chemistry. Three related styles of ore deposits are distinguished in the May Day and Idaho mines — epithermal gold - silver - telluride veins, limestone replacement bodies, and disseminated deposits in porphyry. Past production from the replacement bodies has yielded the richest ore, but the veins are probably responsible for the greater part of the total production. Disseminated ore in porphyry has been recognized but was never mined significantly in the past; it warrants more careful consideration under current conditions. The epithermal gold - silver - telluride veins occupy parts of many of the north - south- striking ore - bearing faults and fractures. Many fault zones are somewhat mineralized throughout their extent, whereas others are totally barren. In nearly all, workable ore bodies are separated by long stretches that contain little or no ore, even though they may contain bodies of quartz and other worthless gangue. Some deposits consist of single well- defined but lenticular veins, but most are vein zones made up of interlacing smaller veinlets. Some veins entirely fill a fault zone; most are narrower than the enclosing shear zone. • January 2007 May Day- Idaho Mine Colorado