The Cecil Whig. [volume] (Elkton, Md.) 1841-current, 1874-09-05
A New Theory of the Formation Of Dia
mtndS.

The natural history of the diamond is
one of the puzzles of geology, the place of
its origin being until recently as great a
mystery as the manner of its formation.
Happily, however, the first part of the pro-
blem has been solved; the diamond has
been Cracked home; and though the pro-
cess by which it attained its crystalline iso-
lation remains as obscure as ever, clue,
at least, has been gained to the conditions
of its development.
We need hardly remind our readers that
in South Africa diamonds are found under
two very dissimilar conditions: first, as
water-worn pebbles associated with pebbles
of quartz, agates, zoolites, and the other
common attendants of the diamond in other
shafts filled with a chalky or clayey earth,
more or less hardened. The famous Coles
berg Kopje is a fair example of the latter
sort, several of which have been discovered
in the Vaal River country. In all these
cases, the diamond bed is surrounded by
rim of rock dipping outward from the CEN
ter, but attaining within short distance
the horizontal position characteristic of
the rocky strata of the district. Inside the
rim or "reef," as the miners call it, the
diamonds are found at home and untravel-
ed; outside they are absent, or occur only
in layers of gravel, itacolumite, or other
products of running or dashing water.
That the gems within the shaft have
rested undisturbed since their formation,
save by the pick and shovel of the miner,
is attested by the nature of their matrix,
which at Colesberg has been mined to the
depth of two hundred feet without any
apparent decrease in the richness of the
yield, by the sharpness of the edges and
angles of the crystals; and still more by
the tendency of the gems thus found to
check, flaw, and even explode with violence
on being brought to the surface and sub
jected to the action of light and air. No
such accidents occur to diamonds found in
drifts, for the simple reason that they are
the survivors of a similar process of natural
selection, all their sensitive comrades hav-
ing been eliminated by exposure in past
ages.
Obviously, if we can decirhcr the geo.
logical history of these singular diamond
beds, very long step will be taken toward
the solution Of the question how the da-
mond originated.
The record begins apparently at a time
when the great interior basin of South
Africa, in which they occur, was the bed of
vast inland sea. The physical geography
of this region reminds one of our own
Utah basin. There is first mountain
ridge from 1000 to 10, 900 feet high, roughly
following the line Of the coast, except
where it crosses the continent toward the
equator, broken only by the Orange and
Limpopo rivers which drain the basin.
Toward the sea the descent is abrupt, often
precipitous; inward, the slope is gradual,
sometimes almost imperceptible, the bot
tom Of the basin lying several thousand feet
below the average crest of the rim. Every
where throughout the interior are abund-
ant and unmistakable proofs of the former
presence of water, filling the basin as a
vast inland sea, at one time the scene of
great volcanic disturbance, more recently
of process of desccation like that which
turned the Sahara from sea to desert, or
that which dried up the sea of fresh water
which, but little while ago, geologically
speaking, filled the now arid Utah basin to
the brim.
The period of diamond production APP
pears to have been while the sea prevailed,
their distribution in the gravels resulting
from the subsequent movements of water,
to which the widespread gravel beds bear
witness. While the sea yet filled the basin,
volcanic action was going on more or less
vigorously, evolving gases, rendng the
everything rock, and producing all the other
we'll known effects of igneous disturbance.
Among the minor effects we can imagine
the formation of vents or crates, to be
filled, when the violence was passed, by the
silly deposits of the sea bed, washed in by
returning water.
Here, then, we have the conditions of
future Colesberg Kopjes-minus the dia-
monds.
Let US follow the process a little further.
A constant product of volcanic action, we
know to be carbonic acid gas, which con-
tains the basis of the diamond combined
with oxygen-a gas capable of being lique-
fled by the pressure of column Of water
less than fourteen hundred feet high, and
the ancient South Africa Sea was several
times that depth. We know that this same
gas is frequently imprisoned in the soft
mud of stagnant pools, where it lies unab
sorbed, escaping as bubbles when the mud
is disturbed. 1t is not unreasonable to
this gas from the heated depths below the
sea bed might be stopped in the muddy
filling of the vents, where, Equefied by the
pressure of the superintendent water, it
might remain until deprived of its oxygen
by some process of Natures chemistry,
leaving the free carbon to crystalize as the
sparkling gem SO eagerly sought for by the
miner.
This, of course, is mere hypothesis, for
we know of no process by which the oxygen
could be so withdrawn; but in every other
respect the superstition is based on known
conditions, and there is apparently no other
way in which the raw material of the dia-
mond could be so readily disturbed in crys-
talzable condition throughout these natur
al diamond factories. The matriX in which
the diamonds are found is unquestionably
of aqueous origin; and we know. from the
vegetable and other substances found en-
closed by diamonds, that they could have
been formed only in the presence of water.
The two seem, therefore, to be contempor-
aneous.
1t is we'll known fact also that diamonds
sometimes contain cavities enclosing a
transparent liquid. We have seen it stated,
but are not sure of the authority, that dia-
monds of this sort have been broken and