The small complex of Kofai may represent a southerly continuation of the Kwandonkaya intrusion (No. 122-00-028) being separated from it by only about 1 km of migmatitic basement rocks. As in Kwandonkaya there are no alkaline rocks. In the core of the complex are gabbros and microgabbros which are net-veined by granites. These rocks are enveloped by later intrusions of biotite granite. Biotite granite also outcrops at Shona Hill 3 km to the south.