Tellurian tennantite, a rare sulfosalt mineral, was discovered for the first time in a pyrite deposit related to mesotbermal-epithermal alteration in Lufeng County, Guangdong Province. As an isotropic mineral, it occurs as irregular grains embedded in pyrite, is lead grey in color and 0.02-0.20 mm in size, and has a Rockwell hardness of 269.3 kg/mm2, with reflection color being grey with a bit brown tone. The associated minerals include tellurobis- muthite and wittichenite. Electron microprobe analysis shows the mean chemi- cal composition of the mineral to be S 24.55%, Cu 41.06%, As 9.86%,Te 18. 29%，Sb 3.58%，Fe 2.505%, Zn 0.11%，and Ag 0.03%, makiag up a chemical formula of (Gu9.995 Ag0.005)10(Fe0.737 Cu0.633 Zn0.028)1.398 (As2.165 Sb0.484 Te1.952)4.60 (S12.595 Te0.465)13. Accordiag to X-ray diffraction analysis, its strongest powder lines are 2.945A，2.563A，1.875A，1.759A and 1.056 A，aad its unit cell parameter a=10.223(A). Planar distribution of elements, reflectance and hardness were determined besides electron microprobe and X-ray diffraction analyses. It is indicated that tellurian tennantite represents a mineral species of tPtrahedrite, and might be used as an important indicator mineral in search for tellurium deposits asso- ciated with pyrite deposits. In fact, the tellurium grade of the mineral has come up to the standard for comprehensive utilization.