Evening star. [volume] (Washington, D.C.) 1854-1972, 1897-08-21
MINING FOR DIAMONDS
Graphic Description of the Methods Followed
in South Africa.
The Kimberley Mines Have Produced
Over Ten Tons of the Precious
Stones since Opened.
From the Chicago Evening Post.

laboratory the wonder Is not that dia-
| monds are found as big ones fist. but
| that they are Lot found as big as ones
head"
The above impressive sentence was spok-
en- by Prof. William Crookes in a remark
! able lecture upon the subject OF diamonds
given AT the Royal Institution in London
! short time ago. This lecture is the most In
teresting and authoritative exposition of
| this subject given in recent years. Prof.
Crookes, who is one of the foremost chem
! lists and physicists of our day, made a trip
of inspection early last year to the African
| diamond fields, and gave in his recent
| speech the results of his travels abroad and
| of the experiments in his laboratory at
home. This lecture deserves to be read in
/ FULL but 1t is Of considerable length, We
| can consider only its most striking and III
| teresting points in this brief review.
The most noted diamond mines, the Kim
| berley, the De Beers, the Dutoitspan, the
Bulfontein and the Wcsselton, arc all con-
| tanned in a circle of ground three and one
! half miles in diameter. The miEcs proper
are irregulary shaped round or oval pipes
extending vertically downward 10 an UNI
known depth. They are filled with broken
fragments of various rocks cementcJ to-
gether by a hard blue clay called blue
ground, In which the diamonds are found.
| At first the mines were worked from above
as stone quarry or gravel pit is worked,
but that system proved unsatisfactory. and
at present underground workings are the
rule. In early days they belonged to diff
ferent people and different companies. bat
| they have gradually fallen into the hands
Of che rich concern. the DE Beers Con-
| solidsted Mines, Limited, which today
owns practically all the valuable diamond
mines in this region. The method of min
ing is to sink shafts in the solid rock at
some distance from the diamond pipes and
then run in tunnels to the blue ground
which is cut away and mined cut by a pc
culiar system that enables the miner to
take out all valuable material and leave the
refuse rock behind.
The System I'm the Mines.
Prof. Crookes says OF this mining: THE
scene below ground in the labyrinth of gal
leries is bewildering in its complexity and
very unlike the popular notion of a dia-
mond mine. All below is dirt, mud. CRIME:
half-naked men. black as ebony muscular
as athletes, dripping with perspiration, are
seen in every direction, hammering, pick
ing, shovaling. wheeling the trucks to and
1ro, Keeping up weird chant which rises
in force and rhythm when A titanic task
calls for excessive muscular strain. The
whole scene is more suggestive of a coal
miiie than diamond mine; and ali this
mighty orga nzation, this strenuous expan-
diture of energy, this costly machinery
this ceaseless toll of skilled and black Ia
Dor, goes On day and night, just to win a
few stones wherewith to deck my lady's
finger"
The work Immediately after the blue
ground leaves the mine looks more like
farming than mining. When the blue
ground Is bro light to the surface IT is as
hard as sandstone and has to be exposed
to the influence of the sun, the air and wa
ter to prepare it for the pulverization neces-
sary later in the work. The hard Jumps and
powders are spread out on the foor ex-
posed to the weather, and are allowed to
stay there with occasional waterings and
harrowings until they begin to crumble
very readily. The friable mass resulting is
then taken to revolving, perforated cylin-
ders in which it is agitated for some time
with water. Refractory Jumps which re-
fuse to pass through the holes are taken
back for more weathering. The material
running through the perforations is led to
immense pans, provided with ten arms. in
which teeth are set spirally. When these
arms revolve and when plenty of water is
made to flow over the pans the very light
stuff is carried away by a waste pipe In
the center, while the coarse material con-
tanning the diamonds collects around the
edges of the pan. By a somewhat similar
arrangement this diamantiferous gravel is
concentrated until the diamonds can be
picked out by hand. The men who pick
over the coarsest gravel are the most trust
worthy employees, since, of course, the
most valuable diamonds are found there.
Sometimes as much $4,000 worth of dia-
monds Is separated in one day. From the
sorting room they go to the office, to be
cleaned and sorted according to value. In
white, black cinnamon, blue. green. pink
and orange diamonds. 1t is quite remark
able that the diamonds of different mines
possess certain distinctive characteristics
which enable experts to know at once from
what mine each stone came.
A Stone Weighing Half Pound.
De Beers and Kimberley diamonds are
large and yellow! Dutoitspan stones are
mainly colored ones Bulfontein-haif a mile
off-produces pure white but small stones;
Jagersfontein yields extremely valuable
gems, with a peculiar steely luster. while
those Of Leicester have a remarkable.
frosty appearance.
Large diamonds rather common: it
would be quite easy to collect in KIM
berley hundred gems which would weigh
an ounce apiece. Prof. Crookes saw set of
eight diamonds, seven of which weighed an
ounce each and the eighth two ounces. The
largest diamond known in the world is one
found four years ago in Jagersfontein. 1t
weighs owe. half a pound, and, though per-
lection in color, is marred by little black
speck in the center. Nearly half ton OF
diamonds are turned out by the Kimberley
mines every year. These mines have pro-
duced over ten tons of diamonds since they
were first opened: an amount more than
sufficient to fill a box five feet square ana
six feet high with these blazing gems: The
supply is so large that the consolidated
company which owns this region mas nao 10
limit the production to keep up the prices.
under pola rized light show the jewels to DE
in a state of tension caused by the imprls-
onment of little colorless gas in the in
terror.
This gas was caught in little hole or
flaw in the stone when 1t was being formed
and is always straining to escape In con-
sequence of this internal tension valuable
diamonds not infrequently explode or fall
into pieces when exposed to heat cunning
dealers sometimes allow unsuspecting and
rich clients to carry in their warm pockets.
or to handle in their warm hands, large
crystals, fresh from the mine, and then II
the stones break the dealer demands salts
faction for the loss of a valuable gem. To
guard against losses due to this explosion
Of diamonds, large jewels are frequently
shipped to Europe imbedded in raw pota-
toes. 1t is most interesting to note that the
artificial diamonds now being prepared ex-
plode just as the natural ones do.
Hardness of the Gems.
Different stones and sometimes different
parts of the same stone vary greatly in
hardness. Some very brilliant diamonds
which came to England from New South
Wales were found to be SO hard that 1t was
impossible to grind them, and they had to
be used for rock drills instead Of Cor jew