Varlamoffite occurs in the greisenized granite, which is on the top of a Nb-Ta mineralized granite stock, distributed in Guonsi. It is intimately associ- ated with brown-black cassiterite. Varlamoffite is orange red in color and semitransparent. The luster is vitreous to greasy and streak is orange-yellow. The spicific gravity is 3.21 to 3.36 and increases to 5.142 at temperature of 1000℃ Difficultly soluble in acids. It is light yellow color in thin section, isotropic, N=1.713-1.715. The varlamoffite is hydrated oxide stannic with formula (Sn0.48Fe0.28Al0.17 Si0.11P0.05As0.01) 0.99H203. It is nearly amorphous, the characteristic lines of X-ray are:3 .30 (msb)， 2.5810 (msb)，1.4105 (vwb).The strongest lines at temperature 1000℃are: 3.3303(100)，2.6317(80)，2.3701(40)，1.7569(70)，1.6731(40) .The unit cell para- meters are: a= 4.6671A.c=3.0959A，z=1, v=67.434A3.It is tetragonal at the temperature 1000℃, space group p4 2/mnm.