Chrysotile fibers were synthesized from glass in hydrothermal conditions. The starting materials were first held at 1650 degrees C and then rapidly quenched down to room temperature. The resulting glass, after the addition of mineralizing agents, was hydrothermically altered in the following conditions: temperature 300 degrees C400 degrees C; pressure 100200 similar to MPa; time 48480 similar to h. X-ray powder diffraction, scanning and transmission electron microscopy were used to examine/study the starting materials and products. Cylindrical fiber morphology was prevalent, but proto-chrysotile was also detected, not entirely showing well-defined crystallinity, as revealed by electron diffraction patterns of selected areas. The mineralizing agent and chemical composition of the glass play an important role in the yield of chrysotile fibers. The effect of growth parameters on the size and abundance of chrysotile fibers is also discussed, in the light of possible recrystallization of glass obtained by thermal treatment of chrysotile-asbestos-containing materials.