The SiO₂ content of tephras was closely correlated with the contents of other major elements except for the K₂O content in Japan tephras, which varied considerably with the volcanic zones where the volcanoes were located. Volcanic glass was abundant in rhyolitic and basaltic tephras and the contents of heavy minerals and plagioclase were high in dacitic, andesitic and basaltic andesitic tephras. Although the heavy mineral assemblage was correlated with the rock types of tephras and volcanic zones in the Japan tephras, these correlations were not clear in the New Zealand tephras. The composition of volcanic glass in andesitic, dacitic and rhyolitic tephras was felsic and non-colored glass with refractive indices about 1.50 was observed. In the mafic tephras, the composition of glass was intermediate and mafic and the colored glass with indices greater than 1.52 was observed. The stability sequence of the primary minerals in tephra-derived soils under temperate and humid climate conditions was graded as follows: volcanic glass < plagioclase = olivine < augite < hyperthene ≦ common hornblende ≦ ferromagnetic minerals. The mobility sequence of the major elements in tephra-derived soils under these climate conditions was considered to be as follows: Cao, Na₂O > SiO₂ > MgO, K₂O > Al₂O₃, Fe₂O₃.