Gold, gold-dust, and iron are among the best known of the mineral riches of Africa, and are the most generally diffused throughout the continent. In the country of Bambouk, in Senegambia, most of the gold which finds its way to the west coast is found. Here the mines are open to all, and are worked by natives who live in villages. The richest gold mine of Bambouk, and the richest, it is believed, yet discovered in Africa, is that of Natakoo--an isolated hill, some 300 feet high and 3,000 feet in circumference, the soil of which contains gold in the shape of lumps, grains, and spangles, every cubic foot being loaded, it is said, with the precious metal. The auriferous earth is first met with about four feet from the surface, becoming more abundant with increase of depth. In searching for gold the natives have perforated the hill in all directions with pits some six feet in diameter and forty or fifty feet deep. At a depth of twenty feet from the surface lumps of pure gold of from two to ten grains weight are found. There are other mines in this portion of Africa, gold having been found distributed over a surface of 1,200 square miles. The precious metal is not only found in hills, the most of which are composed of soft argillaceous earth, but in the beds of rivers and smaller streams, so that the lines of Bishop Heber’s well-known missionary hymn are truthful as well as poetical:-- “Where Afric’s sunny fountains, Roll down their golden sands.” The gold mines of Semayla, which are some forty or fifty miles northward of those of Natakoo, though nearly as rich as the latter, are in hills of rock and sandstone, which substances are pounded in mortars that the gold may be extracted. Barth judged that gold would be found in the Benue river, the principal eastern tributary of the Niger. Gold, silver, iron, lead and sulphur have been found in large quantities, and were long profitably mined in the mountainous districts of Angola. In Upper Guinea gold and iron are deposited in granitic or schistose rocks. The interior contains vast quantities of iron which might be easily mined, but the natives are not sufficiently enterprising to accomplish much in this respect. Gold is also obtained in the beds of some of the rivers of Guinea. In Mozambique, on the east coast, the Portuguese have for a great length of time had a considerable commerce in gold obtained from mines near the Zambezi, in the region near the western limit of that province. It has already been stated that here Dr. Livingstone discovered deposits of coal. Along the Orange and Vaal rivers, in extreme South Africa, have recently been discovered diamond fields which some noted scientists believe will yet prove to be among the richest in the world. [Illustration: ARRIVAL OF THE EXPEDITION ON THE BANKS OF THE ZAMBESI.]