f 64 DISCOVERIES OF THE FRENCH. 
the gold is extracted by agitation in the form of 
dust. In digging deeper the gold is found in 
larger grains, with lumps of emery and lapis lazuli, 
which are entirely covered with this precious 
metal. At the depth of twenty feet it begins to 
appear in small lumps, of from two to ten grains/ 
At forty feet, the greatest depth yet reached, still 
larger pieces are found, sometimes to the amount 
of fifteen grains ; and there is every reason to 
believe, that, on descending lower, the metal 
would be found in still greater abundance. All 
the rivulets, besides, which pass through the plain 
of Natakon, roll golden sands ; and the Colez, 
called by the Portuguese Rio d'Oro, which de- 
scends from the mountains of Tabaoura to the 
Senegal, bears in its bed a considerable propor- 
tion of this precious metal. 
About 40 miles to the north of the mine of 
Natakon, in descending the course of the Rio 
d'Oro, is the mine of Semayla. It is connected 
with the western branch of the same chain of 
mountains, and is situated in a hillock of a simi- 
lar aspect, though not so entirely insulated. This 
hillock is not above 200 feet in height, but it has 
a circumference of nearly 5000 feet. The sub- 
stances in which the gold is contained are here 
very different. About two or three feet below 
the surface is found a species of reddish sandstone 
extremely hard j this is mixed with a species of 
