612 THE POPULAR SCIENCE MONTHLY. 



rounding desert. On the right, toward the east, we may perceive a 

 peak, the summit of which, constantly surrounded with clouds, has 

 never been reached less on account of its height, which is not much 

 more than six thousand feet, than of the precipices and deep clefts 

 which forbid approaching it. It is the peak of Itaube. On the left 

 is seen a less elevated mountain, formed of a single block of rounded, 

 rough-grained quartzite, which has been given the name of Pedra 

 Redonda. From around these two peaks rise the principal brooks that, 

 united, form the Jequitinhonha, a stream the sands of which yield dia- 

 monds to a considerable distance below Diamantina. 



The quartzose rocks predominate everywhere ; the schists are seen 

 only at rare intervals, and in their beds. But those rocks, of which 

 quartz in grains forms the principal element, are different from those 

 we have met in the gold-bearing region. They are more granular, 

 only slightly micaceous ; they pass into real sandstones ; and the beds, 

 generally inclined a few degrees toward the east, are less dislocated, 

 less metamorphic than those of the schists and micaceous quartzites 

 which they cover, and which form an islet on which is situated the 

 city of Diamantina. 



To these quartzites and sandstones are added, on the banks of the 

 Jequitinhonha and some of its affluents, conglomerates of rounded 

 pebbles, the horizontal beds of which occur in the same region on the 

 banks of the Paruna, a stream emptying into the Rio das Yelhas. The 

 schists and the lower quartzites containing green mica appear around 

 Diamantina, and in patches in the bottom of the ravines through which 

 the Jequitinhonha flows. Quartzites, sandstones superior to the pre- 

 ceding, and conglomerates crowning the whole series, such are the for- 

 mations, to which heaps and dikes of diorite should be added, which 

 form the soil of this diamond-bearing basin. 



The surface, in consequence of the nature of the dominant rock, is 

 covered with a bed of white sand marked by brilliant crystals of quartz 

 derived from the numerous veins of that substance which penetrate all 

 the strata. Of vegetable mold there is not a trace, except in the bot- 

 toms of the ravines. In the dry season, a few kylmerias, with knotty 

 trunks and a thick rough bark like that of the cork - oak, humble 

 melastomas with yellow and red petals, and the opuntias, with their 

 straight stems covered with a spiny down, are not sufficient to hide 

 the aridity of the soil. No cultivated fields, but widely scattered 

 houses. Everywhere, however, the ground is dug deeply, and turned 

 over, more by the hand of man than by the action of the elements ; 

 but the only product demanded of the earth is the diamond. 



The region forms a vast ellipse, the major axis of which, running 

 from north to south, extends about fifty miles from the city of Serro 

 to the little river Caethe Mirim, and the other axis more than twenty- 

 five miles from the Jequitinhonha to a line parallel with the Rio das 

 Yelhas. It is, in effect, situated in the valleys of both these rivers, 



