Buru is a carbonatite intrusion of 600x330 m that forms a small 60 m high hill to the southwest of the Tinderet volcano (No. 085-00-047) (Deans and Roberts, 1984). The carbonatite is emplaced in Proterozoic granite gneisses that are brecciated and fenitized in the form of veinlets of aegirine and, more rarely, sodic amphibole (Onuonga et al., 1997). Outcrop is poor the hill being covered by laterised tuff with irregular veins of hematite. However, there are several small outcrops and drilling to about 150 m remained in carbonatite. The carbonatite is a calcite rock which is usually brecciated, veined by fluorite and contains 0.1-0.4% pyrochlore and baryte; monazite, magnetite, biotite, apatite and aegirine are accessory (Deans and Roberts, 1984; Onuonga et al., 1997). The calcite carbonatite is cut by dykes of siderite carbonatite and fine-grained ijolite. An arcuate dyke of calcified microfoyaite is also present. A detailed study of C and O isotopes in the carbonatite has been made by Onuonga et al. (1997).