The times., 1899-08-13
TIE ORIGIN OF DIAMONDS
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Volcanic Action Both Made and
Placed the Gems.
Recent Theories Advanced by Geo
Iogists - The Surroundings of the
Famous South African Mines-siS-
nificance of Moissan's Experiments
Precious stones Found in Meteors.
Frnm the Edinhnrrh Rerieu !

(From the Edinburgh Review)
The great Karoo formation spreads like
mantle over zoe. 600 square miles of South
Africa-east and west from the Spitzkop
to the red heights above Middleburg,
north and south from the Black Mountains
to the Vaal River. It's component beds
were deposited at the bottom of an inland
sea during the Triassic age, when the
Labyrinthodon, or monster toad lizard, led
the van of creation; but their succession
alternated with upwellings Of molten ba-
salt, which spread into level sheets inter
calated between the carbonaceous shales
representing the lacustrine ooZe and the
lacustrine vegetation of an all but endless
epoch. They appear TO have proceeded in
comparative tranquility, those copious
lava foundations. Vehement volcanic ac-
tion was delayed until the complete strait
fcation of the Karoo had been accom-
plished. Provoked, doubtless, by water
infiltrations to the smoldering volcanic
foci beneath, tremendous explosions then
took place, enormous volumes of gas were
evolved, and, irresstibly expanding per-
forated the superintendent rocks with am
pie channels of escape. These did not re-
main empty BY sposmadic efforts, most
likely, not all at once nor all together,
they were replenished from below OF
genuine igneous eruptions no traces re-
main; the work was done by mud-r rushes
transporting upward miscellaneous SUBJ
terranean debris. largely intermixed with
floating reefs s''-fragments that is to say,
torn from the circumjacent stata-the
whole being agglutinated by tufaceous
stuff into volcanic breccia. This vol
canic breccia is the blue ground" of Kim
berey, the indus OF South African dia-
monds.
The Kimberley Mines.
Such, apparently, is the history of these
singular repositories. They are not, prop
erly speaking, extinct craters, but rather
gigantic blow holes excavated catastro-
phicaily refilled gradually. The core ma
terials in each pipe" represent several
''pours'
This blue" rock-named "Kimberlite"
by Prof Carviu Lewfs--is really of dull
green tint, due to its impregnation with
iron oxides. which. appropriating an addi-
tional equivalent OF oxygen on exposure
TO the air, turn yellow and give 10 the up
per sections and subaerial fields their we'll
known ochreous aspect. Essentially the
same material is, however, now eXcavatel
at depth of close upon 1000 feet, as was
struck by the first prospector's pickaxe
thirty years ago. The mines, unless all
the indications at hand prove deceptive,
are bottomless. Their precious contents, in
stead of "petering OUT with descent, grow
more abundant. They We're supplied, per-
haps, by direct Communication with Ieser-
voirs so profoundly subterranean as TO be
accessible only TO those personally con-
Quoted by Virgil or Jules Verne. 1t ap-
pears certain, moreover, that each pipe
was fed from an independent source. Their
| products are separately recognizable. A
trained eye can distinguish De Beers from
kaffeefontein diamonds; those dug within
the range of rife bullet at Bul fontein
| and Dutoitspan show a discernible differ
ence of color; the perfect octahedrons o.
| Newlands resemble neither the irregular
white stones from Wesselton nor the
cross grained" frosted" stones from
Leicester; while the Jagersfontein gems
remind cennoisseurs by their steely glitter
OF the old Indian blues the "Orloff tle
| Regent" the "Sancy''-and fetch proper
tionately high prices.
| Making Carbon Vaporize.
| Our readers do not need to be told that
| diamonds are composed Of pure carbon
Hence, alone among gems, spurious or
| true, they are perfectly transparent TO the
Roentgen rays. Silica, the usual substrat-
| um of jewels, glass paste, crystal, are all
| comparatively Opaque. An easy and in
| falIible test for genuine diamonds has
| thus been Unexpectedly provided by the
| Wurzburg professors memorable discov-
| cry.
| Carbon is an eminently intractable sub
| stance. AT ordinary temperatures no solv-
| ent can be found for it. At no temperature,
| unless by extraordinary compulsion, will
| 1t consent to melt In the electric arc it
| passes directly into vapor, skipping the in
| termediate state.
| The key to the enigma of diamond pro-
| duction should accordingly be found in
| the liquefaction of carbon. The circum-
stances under which it is accomplished
can hardly be other than Identical with
! those attending the development of the
| precious stones. Now, 1t is possible to
determine approximately. by calculations
| based cn the analogy of other substances,
the nature Of those circumstances. This
has been done by Prof. Dewar He finds
| the boiling point of carbon to be 1874 CEN
! tigrade degrees above the absolute Zero
| equivalent to 8, 500 degrees on the ordinary
scale; the critical point is in the neigh
| borhood of $500 degrees (absoute), and
| the corresponding critical pressure
scarcely, if not all, falls short OF fifteen
| tons to the square inch.
! Carbon Dissolved in Iron.
| That fused iron dissolves carbon is no re-
| cent discovery, but the affinity, illustrated
| in the Bessemer process, has been widely
developed and investigated by NJ. Moissan.
| AT the temperature of the electric furnace
he finds this ordinarily intractable sub
| stance to be freely soluble in aluminium,
| chromium, manganese, nickel, uranium
| above all, in boiling silver and iron. I'm
| luckily, it separates from them in cooling,
| as it is deposited after sublimation, not In
the radiant crystalline form, but merely In
| dull flakes of graphite. Only by main
force can the desired substitution of the
| one for the other be effected 1t would
| seem that the intimate marshaling power
in this kind OF matter is virtually annulled
| by a tri1ing separation of the centres from
which 1t emanates. 1t acts only when they
are brought within striking distance by
mechanical means. The difficulty thus rails
| ed is formidable; yet it must be overcome
before the manufacture of the gems enters
upon practical stage. NJ. Moissan was the
first duly to estimate and successfully TO
cope with 1t. His experiments were ground
ed upon careful enquiry into South African
mining conditions.
That stores CT native iron exist deep
| down in the earth's crust has been almost
certified by recent observations. The great
nickeliferous blocks at Ovifak, the
shore of Disko Island. to which a cosmio
origin was attributed by Nordeskiold, their
discoverer are now admitted to be terres-
trial ejecta; and their character is shared
by certain other supposed meteorites Such
masses usually, If not invariably, contain
| a notable ingredient of carbon, and thus
| several lines of evidence converge toward
the inference that the transformation
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