The star. (Reynoldsville, Pa.) 1892-1946, 1909-12-29
TIE BLACK DIAMOND
It Is One of the Curiosities of the
Mineral Kingdom.
A PUZZLE TO SCIENTISTS.

The term "back diamonds" is some.
hines jokingly applied to ordinary coal
which we burn in onr furnaces. but
the real "black diamonds" Of COM
merce are among the most unique min
eral products of the world, and they
serve purpose in the industrial world
that makes them of great value. The
black diamonds are pure carbon and
yet in no outward appearance resem-
Bile the diamonds which we are accus-
toned to wear as ornaments. They
are slightly harder than the crystal or
gem diamonds and. in fact, about the
hardest substance Known.
Black diamonds, or carbons, are
among the greatest curiosities of the
mineral kingdom. They are without
crystalline form and are found in ir-
regular pieces, ranging in size from
half carat up to three, four and FIVE
hundred carats. They are dark gray.
black or brownish in color and Opaque
The real diamond of the jewelry trade
is also pure carbon, but translucent
and crystalline in form. Two objects
so alike in composition could not be
found so opposite in appearance as
these two forms of carbon.
Another peculiar thing about the
black diamonds is that they are found
only in one locality in the world. They
come from very small section of Bra
zil not more than 225 miles square in
area. Outside of this limited territory
no pure black diamonds have ever
been found.
What peculiar freak of nature caus-
ed the deposition of the black dia-
monds in this section of the world and
nowhere else is one of the mysteries
which science has failed to explain.
None of them has been found in the
great Kimberley diamond regions,
where the crystal form of diamonds
have for so long been mined.
The whole origin of the black dia-
mond is, therefore, scientific enigma.
Naturally the question is raised, "Of
what use is a black diamondW No
one would care to wear one of these
diamonds, which resembles a piece of
coal more than real diamond, and so
far no one has popularized the black
gems as the black pearl has been.
Nevertheless the black diamonds serve
a most important and useful function
in the Industrial world
This pure black carbon is not only
ha n 10 Ia hIIt
tougher and not so brittle as the gem.
Consequently it is of great value for
many mechanical purposes and partic-
ularly for boring with diamond drills.
In diamond drilling the tips of the
drills are studded with carbon, or
black diamonds, and when the bores
are deep the pressure is so great that
the gem diamonds would be crushed in
the process But the carbon resists
this continued pressure and slowly
eats down into the rocks.
In diamond drill work the carbon is
set in circular pieces of soft steel or
iron, called bits, and these bits are at
tached to tubing. Armed with these
black diamond teeth, the drills push
their way down under severe pressure
to depth of five and six thousand
feet, cutting through the hardest kind
OF rock, Some black diamonds are
much harder than others, and there Is
no way to determine by the color the
difference In the degree of toughness.
Black diamonds or pure carbon are
not by any means cheap, and the own
ers of the mines in Brazil where they
are gathered are making a good thing
out of their monopoly. There is no
known substance that can take
place of carbon in drills in boring for
gold. silver, copper and other mineral
deposits. Before the black diamonds
OF Brazil were discovered it was i'm
possible to make borings.
When the carbon was first introduc-
ed in our industries it was used in
diamond saws for cutting stones, mar
Bile and similar substances Then the
price advanced so that the carbon was
found too costly for such use and bort
was substituted for stone cutting. Bort
is really an imperfect crystal OF gem
diamond. but it is too brittle for use
IN drills. Consequently bort has tax
en- the place of black diamonds for
stone cutting, and the latter have been
restricted almost entirely to diamond
drilling purposes.
The average size of black diamonds
used in the drills ranges from two to
i've carats, but the larger specimens
give much better results. They cost
more. but they last longer. Conse-
quently there is a greater demand for
the larger pieces of pure carbon, and
the price is sometimes run up to pre-
MUM figures for unusual specimens.
The fear that the supply Of black
diamonds may some day give out and
paralyze the diamond drilling industry
has stimulated prospectors to syste
matte search for new deposits. but so
far they have not been successful. On
the other hand. scientists have been
making close study Of the chemical
conditions which have produced the
black, diamonds, but their manufacture
Is apparently about as difficult as the
making of the gem diamonds. It Is