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INTRODUCTION <br />primary mineral. As in the supergene enrichment zone underground, <br />in the dumps these minerals have in some cases undergone weathering <br />(oxidation) changes into more complex compounds, almost exclusively <br />lead and zinc carbonates (the most common and simplest being <br />smithsonite, zinc carbonate, and cerussite, lead carbonate), <br />sulfates (anglesite, lead sulfate), and numerous and more complex <br />hydrated varieties of both. Such compounds of copper and silver <br />also occur but are extremely rare in the dumps. In general, these <br />changes resulted in increasing molecular weights attributed to <br />carbon, sulfur, oxygen, and water, reducing the relative abundance <br />of lead, zinc, and other metals. <br />These compounds are virtually insoluble in water in the <br />carbonate-buffered environment in which they occur at Aspen.lo <br />Indeed the Roaring Fork River at Aspen, which drains not only the <br />minuscule areas of mining disturbance but also thousands of acres <br />of natural rock exposures and soils containing lead, zinc, copper, <br />silver, and other metals, is remarkably low in metal content. As <br />determined under the Clean Water Act and the Colorado Water Quality <br />Control Act it is a Class I stream, among the purest waterways in <br />the state. Likewise, groundwater wells, even those in areas <br />immediately affected by mining, have shown little or no heavy metal <br />content. Occurrences of more soluble phosphates are extremely rare <br />and are probably associated directly with lawn fertilizing. Metal <br />halides are virtually unknown in the Aspen district. <br />Some of the mine dumps, particularly those of the <br />Millionaire mill and the Durant mine at the base of Aspen mountain, <br />at the Holden Works, and the Mollie Gibson mine, the Smuggler mine, <br />and the Cowenhoven tunnel on Smuggler mountain grew to large <br />proportions readily seen in old photographs. Between the essential <br />cessation of mining in the early 1920s and the 1960s, most of these <br />mine waste dumps virtually disappeared. The waste material was <br />hauled away and liberally used as fill or base material for <br />construction projects, including many buildings, streets and roads <br />in the Aspen area as well as the Aspen airport. <br />30 As opposed to pyrite-rich environments where acid leaching <br />mobilizes carbonates readily, sulfates and oxides somewhat less so. <br />HIUCe A. CO111nS - XX1 - SMUGGLER BIBLIOGRAPRY <br />