The mineral wealth is considerable. There are extensive coal fields, and gold has been found near Tete and Senna.
Livingstone relates that when he visited a hot spring near the Zambesi, he found the valleys near Tete very fruitful and well cultivated.
The whole country lying north and northwest of Tete is hilly. These hills are covered with trees, and present a very picturesque scene. It was in this neighborhood that he found evidences of extensive coal mines, which he felt sure could be worked with little labor and at little cost.
While in the vicinity of the hot spring he availed himself of the opportunity of visiting some former gold washing localities. The banks of the rivulet were covered with large groves of fine mango trees. The Portuguese used to live among these trees while they kept supervision over the natives engaged in the gold washing.
The process of washing the sand of the rivulet was hard and very tedious; for the gold was found in minute scales, like mica.
Towards the west various gold washing stations were pointed out to Livingstone. One station, where gold had been found more abundantly than in any other locality, was supposed by some to be the "Ophir of King Solomon."
He saw at this station gold flakes as large as grains of wheat. He found that the natives would wash for gold only when in need of a little calico.
He was very sure that they knew the value of the gold, for they brought it for sale, packed in goose quills, and demanded twenty-four yards of cloth in exchange for a quill.
They were not unaware of the advantages of this section, for when the waters of the river overflow, they leave a coating of mud upon the banks, and the natives quickly noticed which spots dried soonest, and would begin to dig there, in the firm belief that the gold lay in these spots.
They had a superstition that if they dug deeper than their chins the ground would fall in and kill them.