Synthetic andalusite crystals: morphology and growth features

Abstract Synthetic andalusite Al 2 SiO 5 crystals upto 1 mm were successfully grown under hydrothermal conditions in complex water solutions using a method by Ostapenko. Smaller andalusite crystals (∼0.05–0.1 mm) were obtained in pure water. Face forms of synthesized crystals and growth layers were studied through goniometry, optical and electron microscopy, X-ray and microprobe examinations. The crystal morphology and growth features are reported. The growth rate of {0 0 1} is the highest, 0.04–0.08 mm/day; that of {1 1 0} is the slowest, equals to 0.01–0.02 mm/day. The surface microtopographic observations indicated that adhesive-type growth mechanism operated for the {0 0 1} and the layer-by-layer mechanism for {1 1 0} and, apparently {0 1 1} and {1 0 1} .