Several important questions and apparent contradictions have arisen where asymmetric features of quartz crystals and their partial encrustations have been used to determine the direction of flow of mineralizing solutions.On most of the asymmetric quartz crystals in steeply dipping veins in Arkansas, Bolivia, and apparently, in Brazil, the smaller rhombohedral faces and associated encrustations face upward. Many of these crystals also exhibit well defined discordances in growth habits, as reflected by phantom growth zones. The mutual and spatial relations of these and other features which have been employed as criteria to indicate the direction of flow of mineralizing solutions in deposits of hypogene origin cannot be reconciled readily with the interpretation suggested by Newhouse and others.An alternative explanation, that the smaller rhombohedral faces occupy the downstream side of the crystal, seems more plausible. Careful studies of much more data are needed, however, before an adequate analysis is possible of the various problems involved.

First Page Preview

First page PDF preview
You do not currently have access to this article.