Ferroselite is found in sedimentary uranium deposit in Sichuan province. It occurs in grey一lack sandstone. The ferroselite is dark-grey in colour, with metallic luster on its fresh sur- face. Hv =630kg/mm2(25g)，Dx=7.212g/cm3, refraction colour is from milk-whi- to to purplish, refraction polarizing Rg=purplish, Rm=yellowish-white, RP= milk-yellow to yellowish. Refraction indices are Rg 45.75-57.31(440-660nm)，Rp 39.41-44.50(440-660 nm) and the colour indices of ferroselite are Rvis=50.30, 41.90, X=0.347, 0.341, Y=0.342, 0.340, λd=580nm, 582nm, Pc=0.106, 0.053. The chemical composition of ferroselite indudes Fe 28.64, 27.43,Se 71.59, 71.62 and S 1.00, 0.44,totaling 101.23,99.39. The powder data of ferroselite are:3.04(4,011),2.88(6，101)，2.57(10，111)，2.48(9，120)，2.02(1，121)，1.88(10, 211), 1.79(3,002), 1.69(4,031)，1.58(1，131)，1.53(1,310)，1.456(4，122)，Unit- cell a=4.78A，b=5.755A，c=3.58A，v=98.48A, z=2.