a semiconductor encapsulation material which exhibits a low viscosity and further improved moldability in encapsulation even when highly loaded with an inorganic filler ; an amorphous siliceous powder suitable for the preparation of a resin composition useful as the encapsulation material ; and a process for the production of the amorphous siliceous powder . an amorphous siliceous powder having a content of si and al of 99 . 5 mass % or above in terms of oxides , wherein the al content in the particle size region of 15 μm to less than 70 μm is 100 to 30000 ppm in terms of oxides ; the al content in the particle size region of 3 μm to less than 15 μm is 100 to 7000 ppm in terms of oxides ; and the al content in the whole particle size region is 100 to 25000 ppm in terms of oxides . it is preferable that the / ratio of the al content in the particle size region of 15 μm to less than 70 μm to the al content in the particle size region of 3 μm to less than 15 μm be 1 . 0 to 20 .