97.94 per cent.; Fe203 and A1203 1.98; lime, none; magnesia, trace; total 99.92.
Mr.
Orville A. Derby says of the diamondiferous beds of the Paraguassu
district, " These beds, of which the thickness is estimated at more
than 500 meters, are profoundly disturbed, being thrown into folds
that may be compared to the waves of the sea, and are also cut up by
faults with the uplift sides forming enormous steep-faced cliffs."
These folds produce a series of out-croppings on the mountain sides and
dip now to the east and now to the west. From Santa Isabel to Lencoes,
the conglomerate dips to the east, and forms the eastern slope of the
range. Over the crest it has a western dip after an interval which
exposes a great thickness of the lower sandstone. He says further, "
The points of easiest attack thus far worked are insignificant in
comparison with the masses of material containing the precious stones
still untouched."
All
estimates of the quantity of diamonds mined in Brazil and exported are
little better than guesses. The government claims ownership of all
mines, but is unable to enforce the rights of ownership over the wild
and difficult country in which the diamonds occur. It grants
concessions, and the district authorities impose and collect taxes
where they can, but both are powerless to protect concessioners and
licensees against the native garimpeiros, who not only know the
country, but the diamondiferous gravels, and are experts at picking the
gem out of the material in which it is hidden. With hundreds of square
miles of broken country covered with dense forest and jungle in which
to roam; their only implements a wooden bowl in which to wash the
