Recently forming secondary copper minerals as indicators of geochemical conditions in an abandoned mine in Radzimowice (SW Poland)

2013 Geological Quarterly  
1 In sti tute of Geo chem is try, Min er al ogy and Pe trol ogy, Uni ver sity of War saw, ¯wirki i Wigury 93, 02-089 Warszawa, Po land 2 In sti tute of Geo log i cal Sci ences, Pol ish Acad emy of Sci ences, Twarda 51/55, 00-818 Warszawa, Po land Siuda R. and Kruszewski £. (2013) Re cently formed sec ond ary cop per min er als as in di ca tors of geo chem i cal con di tions in an aban doned mine in Radzimowice (SW Po land). Geo log i cal Quar terly, 57 (4): 583-600, doi: 10.7306/gq.1114 An oc
more » ... r rence of twelve re cently formed sec ond ary cop per min er als (SCM) was ob served in un der ground work ings of an aban doned Cu-As-Au mine in Radzimowice. The min er als, mainly sul phate spe cies, were iden ti fied us ing Pow der X-Ray Diffrac tion (PXRD), scan ning elec tron mi cro scope with en ergy dispersive spec tros copy sys tem (SEM-EDS) and elec tron microprobe anal y sis with wave length-dispersive spec trom e try sys tem (EPMA-WDS) meth ods. The SCM of Radzimowice form the fol low ing as sem blages: paragenesis I is char ac ter ized by langite, posnjakite, brochantite and devilline. These miner als crys tal lise di rectly from pH 6.0-7.0 mine wa ters. Paragenesis II also com prises hy drous cop per sulphates (HCS), and in ad di tion con tains na tive cop per, cu prite, ferrihydrite and gyp sum. Sec ond ary HCS mainly crys tal lise as prod ucts of re actions of sul phate-rich mine wa ters with na tive cop per and cu prite. The pH of these wa ters var ies from ~5.0 to 6.0. The III paragenesis is dom i nated by woodwardite, as so ci ated with vari able amounts of chalcoalumite and amor phous Cu-Al sulphates. Ac cu mu la tions of woodwardite oc cur in the zones where Al-and sul phate-rich acid mine wa ters (pH ~2.5-3.0) mix with neu tral wa ters (pH 6.5-7.0). Paragenesis IV is rare, dom i nated by chrysocolla, co ex ist ing with small amounts of mottramite and goethite. This as sem blage formed as a re sult of mo bi li za tion of sil ica re leased dur ing de com po si tion of rock-form ing aluminosilicates at tacked by acid mine wa ters. green stones, con tain ing in sets of crys tal line lime stone and quartz ite (Urbanek and Baranowski, 1986; Haydu kiewicz and Urbanek, 1986; Baranowski, 1988; Kozdrój et al., 2001) . The meta mor phic rocks are cut by youn ger ig ne ous rocks, mainly rhyolites. The crystallisation age of the rhyolites has been reported as ca. 315 ± 1 Ma (Machowiak et al., 2008) . Within the rhyolites of ¯elaŸniak and Bukowinka hills, gran ites are also found (Mikulski, 2003; Machowiak et al., 2008) . The rar est ig neous rocks are lam pro phyres (Manecki, 1962; Mikulski, 2007; Mikulski and Wil liams, 2010) . The pri mary ore is mainly pres ent in the form of a dozen or so quartz-sul fide veins, of which 6 were un der ex ploi ta tion (Manecki, 1965; Zimnoch, 1965; Paulo and Salomon, 1974; Mikulski, 2005a Mikulski, , 2007 . These crack-type veins cut both the meta mor phic rocks of the Kaczawa Meta mor phic Com plex and the ig ne ous rocks. They run more or less par al lel along E-W direc tion. Dips of the veins are steep (ca. 60-901) and mainly directed to the north. Vein thick nesses vary from a few centi -metres to more than 1 m. The lon gest vein -"Pocieszenie Górnika" -is ca. 2 km long and £1.4 m thick. Bar ren rocks surround ing the veins are hy dro ther mally al tered and usu ally contain dis sem i nated ore min er als. The pri mary ore vein min er al ogy is di verse. The most common pri mary ore min er als in clude: py rite, ar seno py rite, chal copy rite, sphalerite, ga lena, marcasite, tetrahedrite, boulangerite, bour no nite, meneghinite, gold, bis muth and tel lu rium min er als as so ci ated with bar ren min er als such as quartz, rhodochrosite and kutnohorite (e.g., Stauffacher, 1916; Manecki, 1965; Zimnoch, 1965; Sylwestrzak and Wo³kowicz, 1985; Mikulski, 2005a Mikulski, , b, 2007 Mikulski, , 2011 Mikulski and Muszyñski, 2012) . The ore parageneses formed in sev eral mineralogenic stages, and the age of the ore min er ali sa tion de ter mined by the Re-Os method is 317 ± 17 Ma (Mikulski et al., 2005a, b; Mikulski, 2007) . By con trast to the hy dro ther mal parageneses, the weath ering zone of the de posit has not pre vi ously been fully char ac terized. The first notes on the pres ence of sec ond ary spe cies 584 Rafa³ Siuda and £ukasz Kruszewski Fig. 1. Geo log i cal sketch-map of the Radzimowice area (af ter Cwojdziñski and Kozdrój, 1994) Rafa³ Siuda and £ukasz Kruszewski Fig. 5. SEM im ages of sec ond ary cop per min er als from Radzimowice A -spher i cal ag gre gates of woodwardite, B -ag gre gates of amor phous Cu-Al sulphates, C -cracked pitticite co ex ist ing with langite and na tive cop per, D -cu prite crys tals with traces of dis so lu tion, partly cov ered by ir reg u lar ag gre gates of HCS (in di cate by ar rows)
doi:10.7306/gq.1114 fatcat:ywiaj6eeufdjrlay52cwfqmcmy