Feature
Gems & Gemology, Fall 1989, Vol. 25, No. 3
The Growth of Brazil-Twinned Synthetic Quartz and the Potential for Synthetic Amethyst Twinned on the Brazil Law
John I. Koivula and Emmanuel Fritsch
Colorless synthetic quartz that shows obvious Brazil-law twinning has been grown over a seed plate of natural amethyst that is twinned according to the Brazil law. Although commercially available Brazil-twinned synthetic amethyst has not been reported to date, the results of this experiment cast doubt on the long-term usefulness of the so-called twinning test for the separation of natural from synthetic quartz. The twinning, which was readily visible in polarized light, and some "breadcrumb" and tiny fluid inclusions were the only internal features observed in this synthetic quartz when it was examined using a standard gemological microscope.
