Aesthetic improvement of transparent natural quartz by heat treatment at different temperature

Abstract

Attempt has been made by us to improve the aesthetic value of natural gem variety transparent quartz of Odisha through heat treatment with cobalt oxide powder and the results are reported. A series of experiments have been performed at different temperature with cobalt oxide as additive. The change in colour and chemistry on the surface of the treated stones with respect to the untreated one were compared. Visual observation indicated the blue tone and change in its intensity with increase in temperature. Phase change of materials after heat treatment has been analysed using thermogravimetric analysis. Qualitative elemental analysis using electron probe micro analyser confirmed the presence and change in cobalt content in the quartz matrix with variation in the treatment temperature. Moreover, in this work, improvement in aesthetic value of the quartz stone and its consequent change in surface chemical and physical characteristics before and after heat treatment at different temperatures have been compared and described.