Xilingolite occurs on skarn zone developed in the northern side of the iron ore deposit of Chaobuleng field in Xilingola district, Inner Mongolia Autonomous Region, People's Republic of China. tt usually occurs in anhedral granular. forms, or in distinct prismatic, crys- tals. The mineral is lead grey. Density (g/cm3) 7.08 (obs)，VHN50 103.1kg/mm2. In polished section, it is light bluish white under reflected light with a dis- tinct reflection pleochroism, white// e1 to b-axis and bluish white ⊥ ar to b-axis, both in air and oil. Anisotropic properties of the crystal are notable. Reflec- tances measured in air; (wave length, Rmax. Rmin.) 480nm-46.8, 44.3; 546nm- 44.5, 41.8; 589nm-43.8; 40.9; 656nm-43.0, 39.9. Its chemical formula is Pb3xBi2-2x/3S6 where X≈0.3. X-ray single crystal study showed it to be monoclinic, C 2/m, C2 or Cm, ao 13.65, b0 4.078, c0 20.68A，β 93.0°, Z=4. The strongest lines in the powder diffraction pattern are; 3.699(3)(112)，3.386(1)(113)， 3.109(2)(114)，2.932(4)(312)，2.840(2)(115)，2.177(9)(407)， 2.140(1)(209), 2.073(8)(317), 2.051(7)(514)，1.955(7)(0 2 3)， 1.788(6)(2 0 11)。 Although the chemical composition and unit cell parameters of the present mineral are very close to those of lillianite, but the crystal structures of them are different. The name is for the locality.