LAUSR

Abstract (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 β -domeykite, Ni-bearing koutekite and (Ni-Sb)-bearing α -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 ) ∑ 2.94 (As 0.98 ,Sb 0.05 ,S 0.02 ) ∑ 1.06– β -domeykite (simplified formula (Cu 2.7 ,Ni 0.2 ) ∑ 2.9 As 1.1 ); (Cu 3.40 ,Ni 1.40 ,Fe 0.11 ) ∑ 4.91 (As 1.94 ,Sb 0.13 ,S 0.02 ) ∑ 2.08 –Ni-bearing koutekite (simplified formula (Cu 3.4 Ni 1.5 ) ∑ 4.9 As 2.1 ); and Cu 1.97 (Ni 0.98 ,Fe 0.03 ) ∑ 1.01 (As 0.81 ,Sb 0.22 ) ∑ 1.03 –(Ni–Sb)-bearing α -domeykite (simplified formula Cu 2 NiAs). The Rietveld refinement yielded the following unit-cell parameters for β -domeykite 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.