{"id":2331,"date":"2019-10-02T19:49:50","date_gmt":"2019-10-02T19:49:50","guid":{"rendered":"https:\/\/www.gsnv.org\/shop\/observed-and-experimental-pit-lake-water-quality-in-low-sulfidation-quartz-adularia-gold-deposits-nevada\/"},"modified":"2020-02-24T18:17:04","modified_gmt":"2020-02-24T18:17:04","slug":"observed-and-experimental-pit-lake-water-quality-in-low-sulfidation-quartz-adularia-gold-deposits-nevada","status":"publish","type":"product","link":"https:\/\/www.gsnv.org\/shop\/observed-and-experimental-pit-lake-water-quality-in-low-sulfidation-quartz-adularia-gold-deposits-nevada\/","title":{"rendered":"Observed and Experimental Pit Lake Water Quality in Low Sulfidation (Quartz-Adularia) Gold Deposits, Nevada"},"content":{"rendered":"","protected":false},"excerpt":{"rendered":"<p>ABSTRACT<br \/>\nWithin the next 10 to 15 years, over 35 mines in Nevada will<br \/>\nhave lakes in their open pits after dewatering and mining ceases. The<br \/>\nlarge bulk-mineable deposits in Nevada mined below the water table<br \/>\nare of several types, including low sulfidation quartz-adularia Au<br \/>\ndeposits, Carlin-type Au, quartz-alunite precious metal, and porphyry-<br \/>\nCu(-Mo) deposits. The quartz-adularia type systems have<br \/>\nbeen evaluated by sampling from four Nevada open-pit mines that<br \/>\ncurrently contain water, and by conducting static leaching experiments<br \/>\nusing rock and water samples from one example deposit.<br \/>\nDecreases with time in both alkalinity and Ca were observed in the<br \/>\nexperimental waters, as well as the sampled pit lakes, suggesting<br \/>\nthat co-precipitation of metals with calcite and\/or clays as groundwaters<br \/>\ninteract with wall rocks may be an important process in the<br \/>\npit-water evolution.<br \/>\nEach of the four pit lakes studied developed in similar geologic<br \/>\nsettings related to the general characteristics of the ore deposit<br \/>\ngroup, yet the water quality in the lakes exhibits some distinct differences,<br \/>\nparticularly in one of the deposits (Boss). Principal factors<br \/>\ncontributing to differences in water chemistry among the four pit<br \/>\nlakes include variable dilution with surface waters and varying<br \/>\ndegrees of evaporative concentration. In general, pH is near neutral<br \/>\nto slightly alkaline in all of the pit-lake waters, and metals concentrations<br \/>\nare low. Most metals are present in concentrations well<br \/>\nbelow the Nevada drinking water standards. Concentrations of As<br \/>\nare low in three of the four pit lakes evaluated. Water from the Boss<br \/>\npit lake, in southern Nevada, is much more concentrated than that of<br \/>\nthe other three lakes, and some components of concern are also considerably<br \/>\nelevated over predictions based on experimental leaching<br \/>\ntests using the Boss deposit wall rocks and local groundwaters. The<br \/>\ndifferences between the Boss lake samples and the experimental<br \/>\nresults, and between the other three pit lakes evaluated, can be partly<br \/>\nattributed to the location of the Boss pit lake at the edge of a<br \/>\nQuaternary pluvial lake. The addition of pluvial sediments, rich in<br \/>\nevaporitic components, and of surface water that has dissolved<br \/>\nthese, has the potential to contribute high concentrations of Na, Ca,<br \/>\nand SO4. None of the other lakes evaluated have been exposed to<br \/>\nthis influence. The contribution of these elements from a surficial<br \/>\nsource to the Boss pit lake was not simulated in the experimental<br \/>\ntests, which explains the large discrepancy between observed and<br \/>\nexperimental results.<\/p>\n","protected":false},"featured_media":4078,"comment_status":"closed","ping_status":"closed","template":"","meta":{"pmpro_default_level":""},"product_cat":[154],"product_tag":[],"_links":{"self":[{"href":"https:\/\/www.gsnv.org\/wp-json\/wp\/v2\/product\/2331"}],"collection":[{"href":"https:\/\/www.gsnv.org\/wp-json\/wp\/v2\/product"}],"about":[{"href":"https:\/\/www.gsnv.org\/wp-json\/wp\/v2\/types\/product"}],"replies":[{"embeddable":true,"href":"https:\/\/www.gsnv.org\/wp-json\/wp\/v2\/comments?post=2331"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.gsnv.org\/wp-json\/wp\/v2\/media\/4078"}],"wp:attachment":[{"href":"https:\/\/www.gsnv.org\/wp-json\/wp\/v2\/media?parent=2331"}],"wp:term":[{"taxonomy":"product_cat","embeddable":true,"href":"https:\/\/www.gsnv.org\/wp-json\/wp\/v2\/product_cat?post=2331"},{"taxonomy":"product_tag","embeddable":true,"href":"https:\/\/www.gsnv.org\/wp-json\/wp\/v2\/product_tag?post=2331"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}