Anglo Sudan 131 -Egyptian] MINERALS (STONE, Etc.)

an as isolated rocks and boulders chiefly in the plains of Sennar and Darfur . In Sennar , red granite pre dominates, mixed with greenstone and mica -schist; in the Nuba Mountains, Darfur , and Bahr el-Ghazal , grey granite ; and on the Nile - Congo watershed , granite and gneiss . From the Jebel Marra (Darfur) a dyke of white quartz runs west for 30 or 40 miles . In the Nile basin, the cataracts are caused by trans verse ridges and reefs of these hard metamorphic rocks coming to the surface through the eroded sand stones of the river -bed . Over the greater part of the western and central Sudan , south of 13° north latitude, the crystallines are covered by the Nubian sandstone, containing occasional ferriferous beds; but, further south, this is replaced by a ferruginous conglomerate, forming on the surface a rich red earth — theso - called swampore — and continuous with the greatironstone and laterite tableland of equatorial Africa. The Nile Congo watershed is arm of this ironstone plateau, with occasional outcrops of granite, gneiss and quartz The geological section of the Sudan Department of Education undertakes geological surveys and investiga tions , mine inspections, and the collection of geological specimens. It also issues publications and bulletins , the first of which ' was published in 1911 ; from this most of the information given below is derived . The mineral resources of the country , however , are far from being fully explored , and a comprehensive survey would no doubt more than repay its cost .

Alum is obtained in the oasis of Shabb , where there are said to be large deposits .

Antimony is found in the Jebel Marra, near El Fasher, in Darfur.

Coal does not seem to exist in workable deposits , though a lignite of poor quality has been found close to the surface in Dongola province.

Copper is found at Hofrat el-Nahas , situated about 1 Notes on the Mineral Deposits of the Anglo- Egyptian Swan