Rare Pb-Bi sulfosalt mineralization from the Boranja orefield (Podrinje district, Serbia)

Abstract

Pb-Bi sulfosalts are uncommon minerals in the deposits and mineralization of Boranja orefield (West Serbia), one of the less-known Serbian ore deposits. In the Kram locality the Pb-Bi sulfosalts occur typically in skarns associated with garnet, epidote, calcite and magnetite. Pyrrhotite, chalcopyrite, chalcopyrrhotite, valerite, tetradymite, native bismuth, native gold are associated with sulfide phases. Furthermore, the electron microprobe analyses of the Pb-Bi sulfosalts yielded empirical formulae: bursaite (Pb4.81Fe0.03CU0.08Ag0.16)(Sigma 5.08)Bi-3.87(S10.99Te0.06)(Sigma 11.05), Cannizzarite (Pb3.05Ag0.02)(Sigma 3.07)Bi4.00S8.93 cosalite (Pb-1.95,Cu-0.08)(Sigma 2.03)(Bi1.92Sb0.01) S-Sigma 1.93(5.05); aikinite (Cu-0.97,Fe-0.02)(Sigma 0.99)(Pb0.9Ag0.05)(Sigma 1.03)Bi0.95S3.03, All of the Pb-Bi sulfosalts have Bi/Pb atomic ratio in the range 0.8-1.3. Unit-cell parameters were calculated for bursaite and cannizzarite. Orthorhombic unit-cell parameters for bursaite amount to: a = 4.106(5); b = 13.42(2); c = 20.50(3) angstrom; V = 1129.7(2) angstrom(3). The strongest reflections in the X-ray powder diffraction pattern are [d(in angstrom)(I)]: 3.456(100), 3.407(90), and 3.550(56). Monoclinic unit-cell parameters for cannizzarite (Q-subcell) amount to: a = 15.560(6); b = 4.105(2); c = 4.125(1) angstrom; beta = 100.78(2); V = 258.8(1) angstrom(3); and for the H-subcell to: a = 15.470(9); b = 4.096(2); c = 7.000(5) angstrom; beta= 98.53(5); V = 438.3(3) angstrom(3). The strongest reflections in the X-ray powder diffraction pattern are: 3.821(88), 3.337(62), and 3.009(61).