Mineralogy and genetic features of the Cu-As-Ni-Sb-Pb mineralization from the Mlakva polymetallic deposit (Serbia) - New occurrence of (Ni-Sb)-bearing Cu-arsenides

(Ni-Sb)-bearing Cu-arsenides are rare minerals within the Mlakva and Kram mining sectors (Boranja ore field) one of the less-known Serbian Cu deposits. (Ni-Sb)-bearing Cu-arsenides were collected from the Mlakva skarn-replacement Cu(Ag,Bi)-FeS polymetallic deposit. The identified phases include/3-domeykite, Ni-bearing koutekite and (Ni-Sb)-bearing alpha-domeykite. (Ni-Sb)-bearing Cu-arsenides are associated with nickeline, arsenical breithauptite, chalcocite, native Ag, native Pb and litharge. Pyrrhotite, pyrite, chalcopyrite, cubanite, bismuthinite, molybdenite, sphalerite, galena, Pb(Cu)-Bi sulfosalts and native Bi, as well as minor magnetite, scheelite and powellite are associated with the sulfide paragenesis. The electron microprobe analyses of the (Ni-Sb)-bearing Cu-arsenides yielded the following average formulae: (Cu-2.73,Ni-0.17,Fe-0.03,Ag-0.01)(Sigma 2.94)(-AS(0.98)Sb(0.05)S(0.02))(Sigma) (1.06-)beta-domeykite (simplified formula ( CU2.7,Ni-0,Ni-2)(Sigma 2.9)AS(1.1)); (Cu-3.40,Ni-1.40,Fe-0.11)(Sigma 4.91)(-AS(1.94)Sb(0.13)S(0.02))(Sigma 2.08)-Ni-bearing koutekite (simplified formula (Cu3.4Ni1.5)Sigma As-4.9(2.1)); and Cu-1.97(Ni-0.98,Fe-0.03)Sigma(1.01)(As-0.81,Sb-0.22)Sigma(1.03)-(Ni-Sb)- bearing alpha-domeykite (simplified formula Cu2NiAs). The Rietveld refinement yielded the following unit-cell parameters for beta-domeyldte and Ni-bearing koutekite: a = 7.1331(4); c = 7.3042(5) A; V = 321.86(2) A(3), and a = 5.922(4); b = 11.447(9); c = 5.480(4) A; V = 371.48(5) A(3), respectively. Ore geology, paragenetic assemblages and genesis of the Mlakva deposit are discussed in detail and the Cu-As-Ni-Sb-Pb mineralization has been compared with similar well-known global deposits. (C) 2016 Elsevier B.V. All rights reserved.