Zn-tennantite is a rare mineral discovered in a skarn lead-zinc deposit in Inner Mongolia. The associated minerals include chaleopyrite, sphalerite and galena. Zn-tennantite occurs as xenomorphic granular aggregates 0.2-0.5mm in diameter. It is lead grey in color, H_(VRN)=339-388 kg/mm2. Under microscope reflection color is greyish blue with a faint greenish tint.Electron microprobe analysis gives S 25.94, As 10.70, Cu 39.67, Zn 7.36, Sb 9.81, Bi 5.81,Ag 0.18 and Fe 0.37. The calculated chemical formula is (Cu(10.02) Ag(0.03))(10.05) (Zn(1.81)Fe(0.11))(1.92)(As(2.29)Sb(1.29)Bi(0.45))(4.03)S(13), quite similar to the ideal formula (Cu, Ag)(10) (Zn, Fe)2 (Sb, As)4S(13). The x-ray powder pattern of Zn-Tennantite is identical with that of tetrahedrite. Unit cell parameter a0=10.322(). The strongest lines in the powder diffraction pattern are 2.98(A), 1.82(A)and 1.56(A).It is smaller than tetrahedrite.