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Various

"Scientific American Supplement, No. 458, October 11, 1884"


[Illustration: FIG. 1.--DAM ON THE RIBEIRAO INFERNO AT PORTATO DE FERRO.]
We only know the quantity of stones that were discovered during the period
when operations were directed by the Royale Extraccao, from 1772 to 1845,
and this was 269,870 grammes, or more than 1,300,000 carats. It should be
understood that what was taken by stealth does not enter into this total,
and it must be stated that during the latter years, when the Extraccao
existed only in name, smuggling must have been active.
[Illustration: FIG. 2.--ARRANGEMENT OF THE MACHINERY AT THE PORTATO DE
FERRO DIAMOND DEPOSITS.]
Since that epoch the exploitation has been continued by lessees of the
diamondiferous grounds. It is almost impossible to estimate what the
territory has produced. The discovery of the Cape deposits has given it a
terrible blow. Although the Brazilian diamond is much more beautiful, and
for this reason is held at a much higher price, these new exploitations,
by annually throwing large quantities of stones upon the market, have led
to a great reduction in the price, and the Diamantina exploitations, which
have become long, difficult, and costly, have received a serious set-back.


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