Kapfrugwa (Gungwa)

The Kapfrugwa occurrence comprises an irregular body of carbonate-rich rocks lying in the axial area of a tightly plunging antiform of paragneiss (Barber, 1991). Two exposures described by Barton et al. (1991) consist of overlying biotite gneiss beneath which is a 10 m thick layer of apatite-magnetite rock with magnetite-carbonate screens. In one occurrence there is then an underlying 70 cm thick layer of carbonate rock beneath which are granulites. In the second occurrence 6 m of hornblende diopsidite lie beneath the apatite-magnetite rock followed downwards by 170 m of carbonate-magnetite rock. The apatite-magnetite rocks also contain clinopyroxene and aggregates and rhombs of coarsely crystalline carbonate. The magnetite-carbonate rocks comprise 85% dolomite together with rounded crystals of magnetite, diopside and apatite. The apatite-magnetite rocks range up to 11% P2O5, 600 ppm Th and several thousand ppm Ce+La (Barton et al., 1991). Although cautious Barton et al. (1991) and Barber (1991) consider these rocks to be metamorphosed carbonatites. K. Walsh (pers. comm., 2000) is also of the opinion that they are carbonatites and tells me that Dr P. Siegfried has found pyrochlore in them.