Growth and characteristics of some new varieties of coloured quartz single crystals

Methods for the hydrothermal synthesis of four new coloured varieties of quartz have been developed. Two of these varieties are very rare in nature. They are a bi-coloured amethyst-citrine quartz (ametrine) and a phosphorous-bearing low-temperature pink quartz. The other two varieties have no natural counterparts. They are a pink-violet Ni-bearing quartz, and a Cu-bearing quartz which resembles aventurine. The principal conditions for producing these varieties of quartz single crystals are described.