Abstract

This short paper shows the unusual occurrence of SiC whiskers grown in beryl by a supercritical VLS (vapor-liquid-solid) process. The beryl sample is from a small beryl-quartz veinlet related to the Variscan tin deposit Ehrenfriedersdorf in the Saxon Erzgebirge. The SiC or moissanite, often twisted along the c-axis, is of the hexagonal 6H-SiC polytype and generally forms needle- or whisker-like crystals parallel to the c-axis of beryl. Up to now, the growth mechanism is not precisely known, especially for the nature of the VLS liquid catalyst. Nanodiamonds in the supercritical fluid take over the role of the growth trigger. The maximum temperature of the beryl and moissanite crystallization is 720 °C.

Keywords:SiC whisker; Beryl; Supercritical fluids; Nanodiamonds as the catalyst; Raman spectroscopy; Ehrenfriedersdorf tin deposit