Solid inclusions in man‐made quartz crystals (I) microscopic investigations

Abstract

AbstractMicroscopic study of a number of commercial and laboratory quartz crystals grown from Na‐alkaline solutions at about 350 °C show that they always contain fluid and solid inclusions. More than 99% of the inclusions in normally grown crystals occur at the seed plate or very close to it, not further than 0.2–0.5 mm. The solid inclusions occur as single particles, in small groups or in clusters and aggregates containing hundreds of various inclusions. Dimensions of single particles vary from 1 to n · 10 μm but separate inclusions and especially aggregates can measure n · 100 μm. Normally, the number of solid inclusions is of the order of n · 100 per cm2 but in separate “patches” measuring up to several cm2 the density reaches to n · 1000 per cm2. Regardless of the origin of the host crystal, the solid inclusions are always of three kinds: 1. Quartz microcrystals — husks, whiskers, needles, and elongated plates which comprise up to 30% of all inclusions; 2. Several still unidentified non‐quartz phases, tentatively designated as “silicates” — euhedral and anhedral crystals with its refractive index greater than the index of quartz, and fine or submicroscopic elongated crystals of low index, which amount to 70%; 3. Technogene impurities consisting of small irregular opaque particles of metal oxides and presumably graphite which occur only sporadically. The formation of solid inclusions depends probably much more on the surface tension than on mere precipitation.