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9 <br />0 A typical example of Fe(III) water (type A) is that draining <br />the peripheral zone of the Central City Mining District as <br />shown in Table II. Fe(II) and S04 water (type B) is shown <br />by the water from the central zone as shown in Table II. <br />In mine drainages from the Front Range of Colorado the lowest <br />pH is 2.2; Nordstrom (18) found pH values as low as 1.0 for <br />metal mine drainages in Northern California. <br />To summarize, drainages from mines will contain dissolved <br />species in the water due to the typical weathering reactions. <br />These are likely to be Na+, K+, Ca 2+' Mgt+, HC03 , C1-, <br />and SiO2. If the water is in contact with iron minerals, <br />it can be acidic with a pH of about 5. If it is in contact <br />with pyrite, it can contain large amounts of Fe(II) and S04 <br />• and can have a pH of below 3. Note that as the water changes <br />from river water to Type A to Type B the primary constituents <br />change from those normally found in natural waters to those <br />found in an industrial type of water. Nevertheless, the <br />dissolved species in all the waters were derived from the <br />weathering of natural minerals. Also, given time to proceed <br />to the ultimate products, mine water will purify to river <br />water. This fact is the basis behind most methods of mine <br />effluent clean-up. <br />The Secondary Reactions - Other Sulfides <br />The weathering of pyrite will contribute Fe(II), S04 , <br />and H+ to a ground water aquifer, but this does not explain <br />0 the occurrence of other dissolved metals such as Cu, Zn, Cd,