The structural setting and other features of tin-bearing pegmatite dikes peripheral to two small masses of light-colored aplitic granite in intensely deformed Precambrian schist north of the Brandberg massif (an alkaline granite ring dike of late or post-Karroo age) suggest that both the pegmatites and related granites are metasomatic replacements formed by solutions which entered along closely spaced fractures in the schist. Cassiterite occurs with tourmaline in scattered zones of greisenization, or in quartz cores and quartz-filled cross fractures in the pegmatites.

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