Defects in Natural Quartz

Abstract

X‐ray diffraction topographs show at least two types of defects in natural quartz, planar defects which are parallel to the natural quartz faces and needle‐like defects. The planar defects color when exposed to γ irradiation, indicating these are sheets of substitutional aluminum, with an interstitial alkali ion nearby for charge compensation. The linear defects are similar to macroscopic needles of TiO₂ sometimes found in quartz and have previously been associated with dislocations by Lang. Both types of defects show diffraction contrast when observed from different Bragg planes. There does not seem to be a simple relation between either type of defect density and acoustic loss at 300°K in natural quartz.