An Early Precambrian Volcanogenic Banded Barytes Deposit near Vinjamur, Nellore District, Andhra Pradesh, India

A unique 3 b.y. old banded barytic rock formation has been described in intimate association with meta-rhyolitic tuff. The barytic rock is made up of barytes, magnetite, quartz, garnet, tourmaline, epidote, psilomelane and occasionally tremolire and calcite. It is stratiform, being conformable in disposition to the meta-rhyolitic rock with which it is co-folded.

Associated with the stratiform barytes deposits are hematite-quartz bands (tetsukeii in Japanese literature), the presence of which within a volcano-sedimentary sequence marks a horizon of fossil hydrothermal activity and is indicative of the presence of sulphides lower in the stratigraphic column.