Makovickyite and cupromakovickyite from the Obari mine, Yamagata Prefecture, Japan

Yuya IZUMINO, Kazuo NAKASHIMA, Mariko NAGASHIMA
2013 Journal of Mineralogical and Petrological Sciences  
Makovickyite [(Ag,Cu) 1.5 Bi 5.5 S 9 ], and cupromakovickyite (Cu 8 Ag 2 Pb 4 Bi 18 S 36 ), members of the pavonite group, have been found from the Obari mine, Yamagata Prefecture, Japan. Both minerals are the first occurrence in Japan. Makovickyite occurs as irregular particles of 30 -200 μm in the chalcopyriterich ore, and is intergrown with the exsolution lamellae of cupromakovickyite. Both minerals are associated with bismuthinite derivatives (bismuthinite, krupkaite, aikinite), possibly
more » ... inite), possibly cuprobismutite homologous minerals, emplectite, tetradymite and chalcopyrite. The empirical formula of makovickyite is Ag 1.27 Cu 2.60 Pb 0.28 Bi 10.23 S 18 (based on ΣS = S + Te + Se = 18), which is classified as i Cubearing makovickyite. The unitcell parameters from the Xray single crystal of the mineral are a = 13.2524(5), b = 4.0523(2), c = 14.6775(6) Å, β = 99.487(3)°, V = 777.44(6) Å 3 . The empirical formula of cupromakovickyite is Cu 8.66 Ag 2.43 Pb 2.32 Bi 18.07 S 36 (based on ΣS = S + Te + Se = 36). It is inferred that these minerals have been formed by high temperature (more than 300 ºC) hydrothermal solutions in which Bi activity is relatively higher than Cu.
doi:10.2465/jmps.120612 fatcat:67mtfwswnjbldlyiec53b6ebfy