CONDITIONS OF FORMATION OF POLYMETALLIC MINERALIZATION IN THE EASTERN ENVELOPE OF THE KARKONOSZE GRANITE: THE CASE OF REDZINY, SOUTHWESTERN POLAND

Abstract

Newly discovered assemblages of numerous ore minerals disseminated in schists, amphibolites and mylonites at their contacts with a dolomite lens exploited at Redziny, in the northeastern Bohemian Massif, Western Sudetes, Poland, was used in an evaluation of the thermochemical conditions under which specific, and in some cases rare, phases formed. Arsenopyrite, cassiterite and associated base-metal sulfides crystallized at temperatures lower than 550°C. The Ag-bearing sulfosalts pavonite, benjaminite, makovickyite, gustavite, berryite, matildite, giessenite, izoklakeite, cosalite, freibergite and tetrahedrite crystallized along with Ag-bearing galena in the temperature range ca. 350–280°C. They preceded the Cu–Pb–Bi(Sb) sulfosalts wittichenite, bournonite, aikinite-group minerals, emplectite and Ag-poor tennantite, which crystallized from about 300°C to even below 200°C. Kesterite and cernýite crystallized at temperatures about 350°C, cernýite occurring only in Zn-depleted environments. Ferrokesterite and petrukite, occurring with Zn-enriched chalcopyrite as inclusions within (Fe,Cd,Cu,Sn)-enriched sphalerite, are products of decomposition at 340–270°C of a higher-temperature (Zn,Cd,Cu,Fe,Sn) sulfide. Chatkalite formed as a metastable phase at the SnO 2 –SnS equilibrium at temperatures of about 270–260°C; stannoidite crystallized from 270°C to 250–240°C, at which point mawsonite began to crystallize. Unknown Sn-bearing sulfides, with compositions varying between Cu 4 Fe 3 SnS 8 and Cu 10 SnS 8 , crystallized at probably still lower temperatures. Bismuth sulfides (bismuthinite and an unknown Pb–Bi–S phase), sulfoselenides (ikunolite) and sulfotellurides (tetradymite, joseite-A, joseite-B and an unknown Bi–Te–S phase) crystallized under varying conditions: tetradymite at about 300°C, ikunolite at 270–240°C, bismuthinite from about 300 to 220°C, and joseite-A and joseite-B clearly below 240°C.