A hard heavy wood usually black that was traded in ancient Africa?

Ebony. Species of ebony include DiOSpyros ebenum (Ceylon ebony), native to southern India and Sri Lanka; DiOSpyros crassiflora (Gabon ebony), native to western Africa; and DiOSpyros celebica (Makassar ebony), native to Indonesia and prized for its luxuriant, multi-colored wood grain. Mauritius ebony, DiOSpyros tesselaria, was largely exploited by the Dutch in the 17th century. Some species in the genus DiOSpyros yield an ebony with similar physical properties, but striped rather than evenly black (DiOSpyros ebenum).