There are two types of fused crusts of meteorites;the primary and the se- condary. The former may begin to form once the meteoritic body enters the atmosphere of the earth, while the latter may be created on the new surface formed when the meteorite is broken or shattered due to unbalanced stress and strain. The primary fused crust is greyish black, without the original me- teoritic surface characteristics but with evident gaseous prints, vesicles, residue and new accretions formed during falling of the meteorite. The micro stratifi- cation of the crust is distinct, four layers can, in general, be recognized;(I) Hyaline fused crust layer. It is the outmost true fused layer consisting ma.in- 1y of dark glass, incompletely developed, and 0一120µ in thicknesss(II ) Metal particle-dark hyaline layer. Abundant dusty exdissolved metal particles and mag- netite crystallites are found set in a glassy groundmass. This layer is comple- tely developed and from 20 to 160µ thick;(llI ) Bamboo-leaf-like silicate mic- rocrystalline layer. Bamboo-leaf-like microcrystalline silicate minerals are found set in a dark glassy groundmass and this layer is about 260-3001 thick; a.nd ( IV ) Troilite leakage-cemented layer. In this layer, remelting, permeating and cementing phenomena are found only with troilite, and other silicate minerals basically remain unchanged, these producing an obsure boundary between this layer and the underlying one. The thickness of this layer is 200-500µ.