A variety of
TetrahedriteZincian tetrahedrite occurs in a certain Pb-An ore deposit at Mianning, Sichuan. The Pb-Zn ore deposit is primary sedimentary in genesis, which underwent low-grade regional metamorphism. Zincian tetrahedrite was analyzed by electron probe and X-ray powder diffraction. Electron probe analysis of two grains gave: Cu 36.95-37.63 (37.29 on average), Ag 0.58-1.39 (0.99), Zn 7.08-7.53 (7.31), Fe 0.22-0.26 (0.24), Sb 27.19-27.96 (27.58), As 2.37-2.51 (2.44), and S 24.35-24.67) (24.51). The chemical formula is (Cu
9.84Ag
0.16)
10.00 (Zn
1.90Cu
0.14Fe
0.07)
2.11(Sb
3.85As
0.55)
4.40S
13, which is simplified as Cu10Zn2Sb4S13.