weight marketed under the tradename 34 snowtex o 34 and 3 kg of an aqueous solution containing 10 by weight of a partially saponified polyvinyl alcohol having an average polymerization degree of 1700 a product of denki kagaku marketed under the tradename 34 denka poval b 17 34 the resultant mixture was stirred and at the same time concentrated under vacuum to obtain a thick solution having a total al 2 o 3 sio 2 concentration of 31 by weight and a viscosity of 1800 cp under the same operating conditions as those of example 1 this thick solution was converted into the precursor fibers which were collected on a mesh belt the fiber had the gloss of silk by a thermal treatment the precursor fiber was converted into a crystalline alumina silica fiber to 20 kg of a basic aluminum chloride solution having an al cl molar ratio of 1 79 and an al 2 o 3 concentration of 22 by weight were added 5 kg of colloidal silica a product of nissan chemical having an sio 2 concentration of 20 by weight marketed under the trade name 34 snowtex o 34 and 2 kg of an aqueous solution containing 10 by weight of a partially saponified polyvinyl alcohol having an average polymerization degree of 1700 a product of denki kagaku marketed under the trade name 34 denka poval b 17 34 the resultant mixture was stirred and at.