Chrysotile fibers were synthesized from glass in hydrothermal conditions. The starting materials were first held at 1650°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: tempera-ture 300°C–400°C; pressure 100–200 MPa; time 48–480 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 compo-sition of the glass play an important role in the yield of chryso-tile 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 treat-ment of chrysotile-asbestos-containing materials.