gems, diamond, North Africa, Algeria, Sahara, Bled-el-Mass Valley

Diamonds and the indicative minerals (pyrope, picroilmenite, and chromite) are found on a vast area of submeridional elongation of 300 km of the Reggan district in the Algerian Sahara. The Bled-el-Mas ancient valley is in its centre, and here Late Pleistocene alluvials and proluvials are diamondiferous. Diamonds are represented by octahedral, dodecahedral and transitional colorless and yellowish crystals with chromite, graphite and other mineral inclusions. Among the pyropes the knorringite-containing varieties of diamond association is found. As an intermediate diamond source the Early Cretaceous conglomerates are regarded, while their primary source has not yet been established.