SIMPLE MINERALS* 
449 
^1. Natron^ — Of this salt thei^ are two subspe- 
cies, viz. common and radiated, and both are 
found in Africa. The common natron occurs in 
considerable quantity in Egypt, at the town of 
Nitria, also in the valley of the Natron Lakes, and 
in Nubia.* The radiated subspecies is found in 
the province of Sukena, two days' journey from 
Fezzan. It is found at the bottom of a rocky 
mountain, forming crusts, usually the thickness of 
a knife, and sometimes, although rarely, of an 
inch, on the surface of the earth. According to 
Mr Barrow, it would appear also to occur in th6 
district of Tarka, in Bosjesman's Land, in South- 
ern Africa. 
2^. Sulphur,'— substance is met with in 
Darfur. 
^3. Graphite or Black Lead,— it is said to oc- 
cur near the Cape of Good Hope, and also in the 
vicinity of Tunis. 
£4. Gold, — This continent affords a consider- 
able quantity of gold, which is alw^ays obtained in 
the form of dust or rolled masses, and is found 
in the sand of rivers, or the alluvial soil of valleys 
or plains. The northern parts of Africa afford 
but little gold, but in the middle and southern 
regions there are several tracts remarkable for 
* Glauber salt is associated in layers with the natron of 
the lakes. 
VOL* II. J f 
