Diamonds
are found in the talcose chlorite schist, and in a breccia, consisting
of ferruginous clay, quartz pebbles, sand, and oxide of iron fragments;
and also in a secondary bed, accompanied by gold, platina, topaz,
beryl, chryso-beryl, tourmaline, kyanite, amatose, spinelle, corundum,
and garnet. They are found particularly in the valley ot Sejues, along
the rivers Jequetinhonha and Pardo, which run into .the diamond
district. These carry most diamonds by. The dykes and brooks of the
district contain more or less rich diamonds, which are found there in
recent and older beds. Beyond the diamond district, the diamond is
likewise found in the province of Minas Geraes on the Serro de St.
Antonio, in the Serro Frio, and in the rivers Aboite, Andaja, da
Saneno, da Prata, and several other places, such as the right bank of
the Rio San Francisco, and Matto Grosso, and in the beds of Rio Pardo
and Rio Vel-has; in the mines of Riven and Cuithe, and all along the
valley of Peruguado river, in the province of Bahia, in some of the
tributaries of the Rio Doce, on the banks ot the Cachoine. The
rocks in which recently diamonds hav-e been found consist of the
itacolumite, a micaceous sandstone, accompanied by mica-schist,
accidentally traversed by quartz veins. This is the prevailing rock in
the Serro de St. Antonio, in which the Jequetinhonha rises in the Serro
da Matta da Corda, on the eastern slope of which the tributaries of the
Rio Francisco rise; and in the diamond district of Tibagy, very rarely
in the alluvials of ancient rocks. The gold, diamonds, and other fine
stones, are always imbedded in the lower part of the alluvium.
Experience -has shown the richest localities to be in Curran-linho,
Datas, Mendanho, Cavallo-Morte, and Caxoeira de Inferno, where the
alluvial soil is from eight to twenty feet thick, and is composed
almost entirely of silicious sand, strongly colored by argillaceous
iron, which forms a
