Ishiharaite, (Cu,Ga,Fe,In,Zn)S, a new mineral from Capillitas Mine, northwestern Argentina.

MARQUEZ ZAVALIA, MARIA FLORENCIA DE FATIMA; GALLISKI, MIGUEL ÁNGEL; DRÁBEK. M.; VIMAZALOVÁ, A.; WATANABE, Y.; MURAKAMI, HIROYASU; BERNHARDT, H.-J.

Aikita

Seminario; JSPS Bilateral Joint Seminar FY2015 ?Mining and Sustainability: Resource development for Environmental Protection?; 2015

World Forum of Universities of Resources on Sustainability and Aikita University, Japan

Ishiharaite is a new sulfide mineral, (Cu,Ga,Fe,In,Zn)S, discovered at the Nueva Esperanza vein, Capillitas mine (27°27´S, 66°30´W) an epithermal ore deposit belonging to the Farallón Negro Mining District, northwestern Argentina. The mineral occurs as subhedral, equidimensional, individual grains (20 to 50 μm in size), included in tennantite. It is a dark gray metallic mineral, opaque and non fluorescent. Under the polarizing-light microscope, using reflected light, it is an isotropic mineral, and its color is burgundy brown with a faint violet hue in air and violet-burgundy in oil. The main reflectance values are (R1air,R2oil - λ/nm): 18.27,6.77 - 470; 20.10,7.91 - 546; 21.74,8.96 - 589 and 23.94,10.44 - 650. Ishiharaite is cubic, space group F -43m, a = 5.368(1) Å, V = 154.68(1) Å3, Z = 4. The strongest five X-ray powder-diffraction lines [d in Å (I)(hkl)] are: 3.096 (100) (111); 1.897 (60) (220); 1.620 (40) (311); 2.684 (20) (200); 1.097(15) (422). Electron-microprobe analyses of the natural grains (n=22) give an average composition (wt.%) of: S 30.77, Cu 33.61, Ga 13.31, In 9.48, Zn 5.74, Fe 6.13; the average (n=6) chemical composition of the synthetic phase is: S 30.73, Cu 28.05, Ga 15.99, In 11.86, Zn 7.37, Fe 6.13. The empirical formula of the mineral and synthetic analogue, based on 2 apfu, are: (Cu0.54Ga0.19Fe0.12In0.08Zn0.09)Σ1.02S0.97, and (Cu0.45Ga0.24Fe0.11In0.11Zn0.11)Σ1.02S0.98, respectively. The mineral (IMA No. 2013-119) is named in honor of Dr. Shunso Ishihara (b. 1934), Emeritus Advisor of AIST (Advanced Industrial Science and Technology), Tsukuba, Japan.