Selenium rich argyrodite, is a new vanity of argyrodite, found in thb black shale of Bai-Guo-Yan, N. W. Hubei province. Most crystals are irregular graasules: A few grains are perfect octahedron. Twinning on the spinet type. Colour bright black, brittle, strong metallic luster, opaque, conchoidal fracture, streak grayish black. Under the microscope in ref- lected light, it is drak .gray, very weak pleochroism, R=25.5 (λ=546mu). HVHN50-75,D=6.70.Its chemical formula (Ag8.08G0.92Se2.50S3.75) is calculated from the results of chemical quantitative analysis. The data of x-ray diffraction with the Dbye method showed that it is a pseudo-body-ceatered cubic lattice. Psuedo-cell ao=21.44A,.Single crystal x-ray analysis showed that it belongs to the orthorhombic system, ao=15.164 A, bo= 7.511A，co=10.68A入，v=1217A3，z=4. The space group may probably be Pna21 or Pnam. In the 200-500cm-1，the infrared absorption spectrum present obviously four absorbed bands; 426,374,268,and 246 cm-1.On the differential thermal curve, there ate two wide exothernnal peaks folded together in the region of 250-450.