Discovery of the Madimba heavy mineral sand deposit, Mtwara Region, Tanzania

Abstract

Discovery of the Madimba heavy mineral sand deposit, located in Mtwara Region of southern Tanzania, resulted from reconnaissance surface sampling and subsequent follow-up drilling of anomalies >3% total heavy mineral. Two discrete zones of mineralisation have been defined within a host of low to moderate slime sand, known as the Madimba and Madimba East zones, with a long axis up to 3 km and width up to 1.5 km. Limited drilling to date has identified mineralisation from surface to 8 m below surface with grades up 12.36% total heavy mineral. Within the total heavy mineral concentrate, the average valuable heavy mineral content has a range 72–88% for the two zones. Although ilmenite species dominate the valuable mineral assemblage, very high zircon plus rutile components, up to 16% in the total heavy mineral, have been identified. Semi-quantitative chemical analyses of ilmenite and altered ilmenite mineral grains show average TiO2 ranges 50–52% and about 59%, respectively, for both zones. Based on the significant valuable mineral component, good ilmenite composition and proximity to port infrastructure, the Madimba deposits have significant economic potential and could theoretically produce high quality pigment feedstock.