Appearance of as-grown c face in the internal texture of high-quartz crystals collected from Nagatani, Nose-town, Osaka Prefecture

Abstract

Natural quartz crystals are composed of the rhombohedral r{10.1}, z{01.1} and prizm m{10.0} faces. High-quartz exhibits a hexagonal bipyramidal habit with no prism faces or rarely small prism faces. In either low-quartz or high-quartz, the appearance of a basal c{00.1} faces is extremely rare. It has been shown that the faces from the exceptional localities where quartz crystals with basal faces occur have developed by dissolution or overgrowth on the mechanically-broken surface. In the present study, high-quartz crystals with a basal pinacoid from Nagatani, Nose-town, Osaka Prefecture were investigated by means of SEM-CL, and the growth band implying that the c-faces should be directly developed by an original growth process, neither by a dissolution process nor by overgrowth on the broken surface, was first found.