Formation mechanism of tapering of crystals: a comparative study between potassium dihydrogen phosphate crystals and natural quartz crystals

Abstract

A comparative study on the tapering of natural quartz and potassium dihydrogen phosphate (KDP) crystals has been made. Both tapered natural quartz crystals and KDP crystals display similar surface microtopography featuring a large number of tiny elongated growth islands and striations on the tapered regions. In addition to the well accepted fact that trivalent metallic ions in aqueous solution can cause the tapering of KDP crystals, we find that Pb2+ has the same effect. This possibly originates from preferentially settled impurities and embryonic crystallites along the edges between two major faces. © 1995.