SULFOARSENIDES AND ARSENIDES OF Co, Fe AND Ni IN ORES OF ISHKININSKOYE COBALT-COPPER MASSIVE SULEIDE DEPOSIT

摘要

The Co-bearing Ishkininskoye massive sulfide deposit is connected with ultramafic rocks of the Main Urals fault, and its ores are peculiar by increased grades of Ni (up to 0.3 percent), Co (up to 0.2 percent) and Cr (up to 0.3 percent). Sulfoar-senides are represented there by cobaltite, arsenopyrite, and gersdorffite; arsenides -- by nickeline, lollingite, safflorite, rammelsbergite, and krutovite. The last four minerals have been detected in the Urals massive sulphide deposits for the first time. Relations between minerals show that they were formed in the following sequence: nickeline -> gersdorffite -> safflorite, lollingite, rammelsbergite -> cobaltite and arsenopyrite. Nickeline is the purest one without zonality and admixtures -- (Ni_(0.99-1.01)Co_(0.01))_(1.00-1.01)As_(1.00).Lollingite, (Fe_(0.50-0.56)Ni_(0.04-0.35)Co_(0.13-0.06)_(1.03)(As_(1.96)S_(0.04))_(2.00), contains up to 11.12 percent Ni. Composition of safflorite (with up to 10.08 percent Ni and 12.77 percent S) corresponds to formula (Co_(0.83-0.96)Ni_(0.19-0.08)Fe_(0.06-0.04)_(1.08)(As_(2.00-1.98)S_(0.00-0.73)_(2.00). Rammelsbergite, (Ni_(0.49-0.88)Co_(0.29-0.10)Fe_(0.23-0.04)_(1.01-1.02) (As_(1.96-1.92)S_(0.04-0.08)_(2.00), has increased contents of S, Fe and Co: up to 1.34 percent, 1.37 percent and 7.64 percent, respectively. Krutovite, (Ni_(0.76-0.91)Co_(0.17-0.08)Fe_(0.06-0.02)_(0.99-1.01)(As_(1.54-1.74)S_(0.46-0.26)_(2.00), has also increased contents of Fe, Co and S: up to 2.29 percent, 5.03 percent and 8.27 percent, respectively. Moreover, rammelsbergite and kruitovite have increased contents of Bi (up to 0.97 percent) that could be recalculated on formulae units. Cobaltite, (Co_(0.84-0.43)Ni_(0.12-0.42)Fe_(0.08-0.17)_(1.04-1.02)As_(0.98-1.03)S_(1.02-0.97), and arsenopyrite, (Fe_(0.89-0.49)Co_(0.10-0.07)Ni_(0.05-0.45)_(1.04-1.01)As_(1.02-0.39)S_(0.98-0.61), despite their varying compositions, both are very rich in Ni: up to 14.69 percent and 14.66 percent respectively. Their unit cell parameters reflect the increased amounts of Ni and Fe in the structure and are as following: cobaltite -- a = 5.599(3) A; b = 5.607(1) A; c = 5.610(2) A, V = 176.1; arsenopyrite -- a = 5.747(3) A; b = 5.687(1) A; c = 5.776(3) A, V = 174.5(2). Gersdorffite, (Ni_(0.30-0.72)Co_(0.24-0.20)Fe_(0.22-0.16)_(0.97-1.08)As_(1.10-1.15)S_(0.90-0.85), has the increased Co and Fe contents -- up to 12.68 percent and 18.53 percent respectively. All sulfoarsenides have zonal structure.