REV05461 - Laserfiche WebLink

Home Browse Search

C~BVvOLD MNG. CO. ID~~19-fi39-324 FEB 03'94 8:18 No .003 P.03 exmeme metal concenastiont beeausc they drain aline workings (not mine dumps) in deposits • where sulfides are contained in discttte veins, and thus have access [o only limited voluttrs of sulfides and rock materials during weathering. The stxond type of waters are those which drain molybdenite- and fluorite-rich waste dumps of the C71max porphyry molybdenum deposit (McNulty Gulch sample, Table 3): that waters fall in the high-acid, high metal class (Figure 2). Low pII values (near 1.9) prcsuu~ably rcsul[ from the tntidadon of pyrite ptrsent in the waste dumps and the lack of buffering nracdons with the silicato-rich dump mazerial, however, non-extreme Zn and Cu concentrations (20-40 ppm each) probably tetlect the sclailvcly low amounts of sphalerite and chalcopyrite in the Climax ores. Due to the large amottnta of fluorite in the waste dump material and their low pH, lire Climax dump waters have extreme Fluorine concentrndons near 900 mg/L. Interestingly, tuanium is the dominant moral in the Climax waters other than iron and alttarinum: the eztrttne U conccnnadons near 90 ppm most likely result from the low pH of the warrss, the U~nrichcd granitic intrusive hoe[ rocks, and ilte high availability of F in the waters to complex the urtudura Acid-low metal Two tlraittarpet rarapltd to date have acid pH values but carry low dissolved base metals (less than 1 ppm sum of metals); these include the Pau-Me-By shine near Stunmitville and the natural acid tlraitmge along South Mineral Crtxk near Silverton (Fig. 1). Both these watts drain pyito-rich tfissetninated sulfide rt»nerttluadon in rocks with moderate to low acid buffrstrtg capatslty. Both have low dissolved oxygen i< 5 ppm) but high sulfate (500.660 ppm) and dissolved Fc (50.140 ppm). The lack of base metal transpon by these waters may be due to (1) low t:atounts of base metal sulfides in the ate deposits, and/or (Z) the noted far ground waters to have dissolved oxygen daring weathering ro stimulate microbial catalysis of sulfide oxidation (Nordstrom, 1982}. Near-neutral waters with extreme, high, and low metal content Drainages wlth the highest pli values txcta in deposits with high acid buffeting capacities, including those with (1) carbonate host tucks err abundant carbonau gangue mint:zals (I.eadville Urain, liandora, French Oulch, Kokomo mines), (2) host rocks altered to calcite-rich propylitic ts+incral essemblagrs (volcanic-hosted epithermal deposits drained by the Rowley Tunnel (Sonanra district] and American Tunnel [Eurel~ district)), or (3) host rocks containing abunriantrtacdvo aluminosilicate glasses (some volcanic-hosted epithetmal deposits (Miner's Creek at Ctrede], and Au-Te deposits at Cripple Creek [Calton Tunnel]). Hhst-rock composition can significantly affect water concentrations of sturte dissolved species. For example, wants which have interacted exteruively with fe]aic vdcanic rocks generally contain elevated Na (IU-80 ppm), K (1-10 ppm) and Li (1U-30 ppm). Near•neuval waters with high to extmme dissolved base meta! contenu (as highas 270 ppm SM) drain nrincs in pyrite- and sulfide-rich deposits (Bandota, Rowley, I.eaeiville Dmin, French Gulch. Kokomo). These include waters with tow DO (< 0.1 ppm) that carry no hydrous Fc-oxide (tIPO) particulates in suspension, and waters with high DO (up to 8 ppm) that carry some iiF'O particulates. 7.inc is generally the predominant heavy mere! in [hose ' waters. The abundance of Zn reflects dtc lack of sorption by particulate HFO (Smith et al., thLs volume;; Smith et al„ 1992) Near-neutral waters with ]ow base metal concentrations form itt deposits with low pyrite contents (Carlton, Swathmorc, Huron, Miners Creek, Dauntless). DO concentrations in these waters also vary widely. SUMMARY OF CONTROLS ON DRAINAGE COMPOSITION The dominant controls on drainage composition in divexse orz deposit types include geologic conrols (such as mineralogy, host rerck alteration, etc.), exurnal controls (such as •