Process for producing amethyst crystal

Abstract

Abstract A process for producing amethyst crystals which involves growing colourless quartz crystals by a hydrothermal method of a temperature drop in a high-pressure autoclave on crystalline quartz seed plates oriented parallel to pinacoid crystallographic planes {0001} or to planes inclined to said pinacoid planes at an angle of up to 15° with the use of silica as a charge, said growing being effected from aqueous solutions of ammonium fluoride with a concentration of from 5 to 30% by weight and containing iron introduced into the autoclave in the form of its oxydic or hydroxydic compounds in an amount ranging from 5 to 30 g/l of the solution. Said growing of colourless quartz crystals is effected at a crystallization temperature within the range of from 150° to 500°C under a pressure of from 10 to 1,200 kg/cm 2 and at a crystal growth rate of from 0.05 to 1.5 mm/day. It is preferable to introduce inorganic compounds of lithium or sodium into the autoclave, prior to the crystal growing, in an amount ranging from 0.5 to 2.0 g/l of the solution. The resulting grown colourless quartz crystals are exposed to an ionizing radiation. In the process of the present invention the crystal growing is effected under specified physico-chemical process parameters enabling a good reproducibility of said process. Crystal growth rates are high enough and the process according to the present invention makes it possible to produce amethyst crystals with a high colour purity (without any smoky tint) and with no cracks whatsoever.

Inventors

• 👤 Vladimir Sergeevich Balitsky
• 👤 Lev Nikolaevich Khetchikov
• 👤 Valentina Petrovna Orlova
• 👤 Ljudmila Vasilievna Balitskaya

Bibliographic Details