The diamond is found under three conditions: (1) in the gravels of the present rivers, embedded in a ferruginous claycemented conglomerate known as cascalho; (2) in terraces (gupiarras) in a similar conglomerate occupying higher levels in the present valleys; (3) in plateau deposits in a coarse surface conglomerate known as gurgulho, the diamond and other heavy minerals being embedded in the red clay which cements the larger blocks.
The Sugar Plantations: The soil of the island is of considerable fertility; it is a ferruginous red clay, but so largely mingled with stones of all sizes that no plough can be used, and the hoe has to be employed to prepare the ground for cultivation.
In their upper courses all the southern affluents of the Ghazal flow across a plateau of ferruginous laterite, their valleys having steep banks.
Masses of laterite, buried in hard ferruginous clay, crop up as rocks or slabs.
In the central portion, which belongs to the Triassic formation, magnesian limestone, ferruginous sandstone and gypsum are representative rocks.
Copper is widely distributed in nature, occurring in most soils, ferruginous mineral waters, and ores.
Cold mineral springs are at Bartfa, with alkaline ferruginous waters; Czigelka, with iodate waters; Parad, with ferruginous and sulphate springs; Koritnicza or Korytnica, with strong iron springs; and the mineral springs of Budapest.
Of the town are the baths of Banko, with alkaline and ferruginous springs, and about 12 m.
It is celebrated for its medicinal waters, of which the Alexisbrunnen, a ferruginous spring, is used for drinking, while the Selkebrunnen supplies the baths, which are of use in feminine disorders.
It is indigenous to the south of Spain and the north of Africa (where it is known as Halfa or Alfa), and is especially abundant in the sterile and rugged parts of Murcia and Valencia, and in Algeria, flourishing best in sandy, ferruginous soils, in dry, sunny situations on the sea coast.