The gold leaf. [volume] (Henderson, N.C.) 1881-1911, 1909-12-02
THE BLACK DIAMOND
1t Is One of the curiositieS of the
Mineral Kingdom.
A PUZZLE TO SCIENTISTS.

Nature Has In Some Peculiar Way
Produced This Rare Form Of Carbon
and Then Thrown Away the Secret
Of the Process-Found Only In Brazil.
The term "black diamonds" Is some
times jokingly applied to ordinary coal
which we burn in our furnaces. but
the real "black diamonds" OF COM
merce are among the most unique min
eral products of the world. and they
serve a 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 cdrbons. 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 a 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
I'll 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 black diamOndT' No
one would care to wear one of these
diamonds. which resembles piece OF
! coal more than a real diamond, and SO
far no one has pepularized 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
harder than the real diamond. but
tougher and not so brittle as the gem.
Consequently 1t 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
|
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
| in bn
| 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 the
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.
bic 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 au imperfect cryatal or gem
diamond. but it is too bri for use
In drills. Consequently he has TAX
en- the place of black diamonds fol
stone cutting. and the IL tier have been
restricted almost entirely to diamond
drilling purposes.
The average size of black diamonds
used In the drills ranges from two tt
i've carats. but the larger specimens
give much better results. They cos1
more, but they last longer. Conse
Qu.ltly there is Il greater demand fol
the larger pieces of pure carbon. ane
the price is sometimes run up to pre-
MUM figures for unusual specimens
The fear that the supply of h!act
diamonds may some day give out arr
paralyZe the diamond drilling induSt!
has stimulated proSpectorS to syste
matte search for new deposits but 81
far they have not been successful Or
the other hand. scientists have beer
making a close study of the chemica
conditions which have produced th,
black diamonds. but their luanufactur,
is apparently about aS difficult as til,
making of the gem diamonds 1t i.
possible under certain conditions Il
make either, but not in sizes sufficien
to be Of any commercial value Ma
ture In some peculiar way has mad,
these rare products Hs.,i then thrown
the secret Of the PROCESS away. Ii an,
man can ever unlock or find that Sc
cret he may cause Il panic in the dia
mond trade-Scientific American.