The Yale expositor. (Yale, St. Clair County, Mich.) 1894-current, 1910-07-15

a n United States is its largest
4ks~ market. 1t is found in La
Chapada and Lavras districts
of the province of Bahia, Brazil,
where 1t is mined from river beds and
other alluvium. The miners sell their
.nnd TO agents of exporting firms In
the city of Bahia 1t is calculated that
this port ships annually about $4,000
600 to $4600,000 worth of black dia-
monds, and, with the adoption OF
modern methods and machinery In
place OF the extremely primitive ones
formerly employed, the industry will
be tremendously stimulated. About
twenty-five years ago a stone of LOO
carats was found, followed by one of
100 carats, and in 1895 gigantic
stone Of S,07S carats, or els grams.
which was purchased by New York
house for sac, 900 and broken up into
pieces of suitable size for diamond
drills. At present prices this stone
would be worth about $4,000. Dur
ing tbs past ten years stones of 400
10 500 carats have been discovered.
while they are frequently found weigh
ing from 100 to 200 carats.
Previous to 1870 carbonate was
practically yalueless. From 1870 to
1872 it was employed as an abrasive
for cutting and polishing the white
gems, and thousands of carats were
sold at 80 cents per carat, to be crush
I'd to powder for this purpose. A few
years later, when carbonate was en-
ployed in diamond drilling, IT sold at
from 81 to 81 a carat. Between 1895
and the present the market value has
fluctuated between $25 and SIS carat
this high price being caused by the
decline in the supply of carbonate in
the past ten years, while the demand
has increased. in connection with the
subject of black diamond consumption
in drilling, it is interesting to remark
that in digging the drill hole at Ryb-
mix (Paruschowitz) Upper Silesia,
which attained depth of nearly 1000
feet, upward of $4,000 worth of car
honado was used.
The conditions are entirely differ
ent from those OF Africa. The gravel,
sand, and other material containing
diamonds lie in or near the beds OF
streams and rivers, and have been
washed down by erosion from high
-'chapadas' or plateaus, which are
probably the original matrix in which
Brazilian diamonds were formed. AS
is natural, gold and variety of other
substances, such as itacolumnite.
,olivine, limestone, hematite, granite,
gneiss, and clay are associated with
the diamonds. The diamond bearing
material of Brazil consists of con-
glomerate, sometimes fnterbedded with
hard yellow sandstone, which is wash.
ed down through erosion by rivers, or,
in some cases, may be badly decom-
posed and rotten rock. Fossils are
generally lacking. The deposits often
consist of schists and schistose clay
-diamondbearing clays. reddish earth
granite and gneissic formations and
pebbles of various sorts.
The states of the republic which
have yielded diamonds are Minas
-Geraes, Parana, Bahia, Goyaz, and
Matto Crosse. 1t is in the first named
that Diamantina. celebrated for the
rich diamond mines in its vicinity, is
situated. The city is we'll built and
lies at the headwaters of the Jequitin.
honha, or Diamond. river, a stream
$50 miles long, which empties into the
Atlantic at Belmonte. To the east OF
Diamantina is the peak of Mount
Etambe, $500 feet, in the Sierra Espin
AGO Range. The mines are situated
north of Rio de Janeiro, 500 kilo
meters, or ,497 miles, north OF Ourc
Preto. the capital OF Minas Geraes
The territory in which they are stu
ated forms a vast ellipse, so kilo
meters, or so miles, by 40 kilometers
or rs miles, In a plateau 1000 to 1,20t
meters 1890 to 1897 feet), contain
ing number of valleys cut by the
Jequintinhonha and its left tributaries
Ribeirao do Inferno. Rio Caethe. etc.
and also by the Sac Francisco's af
huents which flow to the northwest, IN
a very different basin.
Although diamond mining has beer
more extensively and systematically
pursued in the states of Minas Geraes
and Bahia than elsewhere In Brazil
Matte Crosse. Goyaz. and Parana have
yielded sufficient results to justify Oh,
belief that their future as centers o
diamond production will be prosper
Gus.
The primitive methods OF mimi,
employed in Brazil until recent years
have. nevertheless. abundantly re
veaIed the natural productiveness o
the Brazilian diamantiferous deposits
Two native methods are still yer,
largely In use. according TO the local