Occurrence of a Montmorillonite Mineral in the Nigerian Younger Granites at Ropp, Plateau Province, Northern Nigeria

Abstract

A B S T R A C T: A montmorillonite mineral occurs in the marginal facies of a biotite-granite in the younger granite ring-complex at Ropp, Plateau Province, Northern Nigeria. The mineral is associated with the development of silexitic textures (pegmatitic knots and miarolitic cavities) filling the spaces between euhedral crystals of quartz, perthite and biotite protruding from the walls. Chemical, X-ray and differential thermal results suggest that the mineral belongs in the beidellitenontronite series; it is thought to be primary in origin.