VANADIUM GROSSULAR FROM THE MOZAMBIQUE METAMORPHIC ROCKS, SOUTH KENYA

Green vanadium grossulars occur as porphyroblasts in calc-silicate-gra phite gneiss associated with marble, pelitic-psammitic gneiss and gran itoid gneiss in the Mozambique metamorphic belt, south Kenya. Calc-sil icate-graphite gneiss contains scapolite, vanadian zoisite, vanadian d iopside, vanadian sphene and vanadian magnetite, in addition to vanadi um grossular. The vanadium grossular porphyroblasts are mantled by a k elyphitic rim that consists mainly of symplectic intergrowth of fine-g rained scapolite, vanadium grossular, vanadian diopside, vanadian sphe ne, vanadian magnetite, plagioclase, calcite and quartz. Vanadian mine rals (vanadian muscovite, vanadian zoisite, vanadian sphene and vanadi an rutile) also occur in the marble. The occurrence of scapolite and t he enrichment in vanadium suggest that the protolith of calc-silicate- graphite gneiss was evaporite or related sediment. The mode of occurre nce of vanadium grossular in Kenya is quite similar to that in the Ssr Rondane Mountains, East Antarctica. The vanadium-grossular-bearing gn eisses in Kenya might be correlated with those in Antarctica, since th e Sor Rondane Mountains had continued from the Mozambique metamorphic belt before the breakup of Gondwanaland. Copyright (C) 1996 Elsevier S cience Ltd