The Murchisongreenstonebelt is a 140km long, typicalJy 5 to 10km wide, Archean schist belt situated in the Eastern Transvaal Lowveld in the north-eastern part of the Kaapvaal Craton, South Africa. Schlumberger electrical soundings and a gravity survey were carried out in the area to study the deep structure of the greenstone belt as well as that of the surrounding granite-gneiss terrain. The economic importanceof this geological feature derives primarily from the fact that the minesalong the Murchison belt aremajorproducersofantimony. The resultsoffifteen deep electrical soundings (maximum current electrode spacings of 4 to 40 km) show that the rock assemblage in the schist belt has a resistivity of less than 5,000 ohm m and more typically 1,200 ohm m, while the intrusive Rooiwater Complex and the surrounding granite-gneiss terrain have resistivities in excess of 10,000 ohm m. Geoelectrical models indicate thicknesses of up to 7.5 km for the greenstone assemblage. A gravity survey comprising 720 data points was done in the area. The main feature on the Bougueranomaly map of the Murchison belt and environs is a relativehigh of up to about 250 g.u. that runs along the entire length of the belt and reaches its largest amplitude over the Rooiwater Complex. Density determinations were done on 47 samples representing most rock types in the area. Two-dimensional modelling of the residual gravity anomaty was done along a profile crossing- the belt. The results are in agreement with the resistivity models and a structural model in which the greenstone belt could be one limb of a synclinal structure.The Murchisongreenstonebelt is a 140km long, typicalJy 5 to 10km wide, Archean schist belt situated in the Eastern Transvaal Lowveld in the north-eastern part of the Kaapvaal Craton, South Africa. Schlumberger electrical soundings and a gravity survey were carried out in the area to study the deep structure of the greenstone belt as well as that of the surrounding granite-gneiss terrain. The economic importanceof this geological feature derives primarily from the fact that the minesalong the Murchison belt aremajorproducersofantimony. The resultsoffifteen deep electrical soundings (maximum current electrode spacings of 4 to 40 km) show that the rock assemblage in the schist belt has a resistivity of less than 5,000 ohm m and more typically 1,200 ohm m, while the intrusive Rooiwater Complex and the surrounding granite-gneiss terrain have resistivities in excess of 10,000 ohm m. Geoelectrical models indicate thicknesses of up to 7.5 km for the greenstone assemblage. A gravity survey comprising 720 data points was done in the area. The main feature on the Bougueranomaly map of the Murchison belt and environs is a relativehigh of up to about 250 g.u. that runs along the entire length of the belt and reaches its largest amplitude over the Rooiwater Complex. Density determinations were done on 47 samples representing most rock types in the area. Two-dimensional modelling of the residual gravity anomaty was done along a profile crossing- the belt. The results are in agreement with the resistivity models and a structural model in which the greenstone belt could be one limb of a synclinal structure.