Cetineite, a new antimony oxide-sulfide mineral from Cetine mine, Tuscany, Italy

Cetineite, a new Sb oxide-sulfide mineral, occurs as tufts of acicular orange-red crystals in slag cavities in the dumps of the Cetine mine, Tuscany, Italy. Probe anal. gives a formula very similar to (K,Na)3+x(Sb2O3)3(SbS3)(OH)x (2.8-x)-H2O, with x ≈ 0.5. The mineral is hexagonal, P63, a = 14.230(2), c = 5.579(1)Å, Z = 2. The strongest lines of the x-ray powder pattern are given. The calcd. d. is 4.21 g/cm3 and the mineral is optically uniaxial (+) with birefringence 0.059; cleavage {100}; and microhardness (VHN20) 127-156 kg/mm2. The IR spectrum is reported.