Tennantite-(Ni), Cu₆(Cu₄Ni₂)As₄S₁₃, from Luobusa ophiolite, Tibet, China: a new Ni-member of the tetrahedrite group

Abstract The new mineral tennantite-(Ni), Cu 6 (Cu 4 Ni 2 )As S 13 , has been discovered from the Luobusa Chromitite, Tibet, southwestern China. Tennantite-(Ni) occurs as anhedral grains ranging to 20 μm in size. In reflected light microscopy, tennantite-(Ni) is isotropic and appears yellow-greenish grey. Reflectance data for Commission on Ore Mineralogy wavelengths air are: 31.0 (470 nm), 29.6 (546 (589 nm) 29.3 (650 nm). Electron microprobe analysis holotype material gave empirical formula (on basis of total cations = 16 apfu): M (2) (1) [Cu 4.00 (Ni 0.97 0.53 Fe 0.50 ) Σ2.00 ] Σ6.00 X (3) (As 2.94 Sb 1.06 Σ4 12.77 . cubic, with space group I $\bar{ 4}$ 3 m (#217), a =10.2957(9) Å, V 1091.4(3) Å Z 2. By using single-crystal X-ray diffraction, crystal structure determined refined final R 1 0.0423 163 independent reflections [ F o > 4σ ( )]. calculated seven strongest powder diffraction lines d hkl )] 2.972 (100) (222), 1.820 (83) (440), 2.574 (28) (400), 1.552 (18) (622), 3.640 (10) (220), 1.880 (521) 1.287 (7) (800). isostructural other tetrahedrite-group minerals, nickel hosted at tetrahedrally coordinated site, along minor Fe. its name have approved by New Minerals, Nomenclature Classification International Mineralogical Association (IMA2021-018).