St. Tammany farmer. [volume] (Covington, La.) 1874-current, 1891-12-19


GEOLOGY OF DIAMOND FieloG
$500 q he KinSssssy lGlnss =
0eatA AfelsA.
The principal diamond miues IN South
Africa are within space Of two miles
square, and there Il every reason to -
lieve that they arc connected st . ~
mote depth, because the peculiar pipe
or chimney foa matioa Of each mine hos
been clearly shown down 70 - depGA q
ever six hundred '1eet and ths
walls Of the mines trend toward tho
central one. .
From the surface indications II WAS
difficult to determine the geology ofths
country. and had It not been Tor the %,
cidental finding Of diamo6ds in the sur
face soil there was nothing to Indicate
. peculiar diamond bearing formation.
The surface soil was . hard red saay
lbout ten feet in depth, and beneath
this, after the mines were opened. were
found the measures of the sub-earbontf.
erous. which extended down to . depth
.of two hundred and ninety-five feet.
Beneath these measures IN unstratihed
bassltic rock was found, which should
be classed a. IN amygdaloidal dolerits
with much agate distributed through It
When the mines were well opened 1t
became easy TO observe the uptiited
strata of the sub-carboniferous meas
urcs. which were tilted all around the
mines as If an upheaval had occurred
from one central point
This was true Of each mine and =
exactly what has taken place. for
through the hard dOlerite and the even.
measures above it and from some UNI
known source, nature in some gigantic
throc forced mp these pipes as vents OF
safety . strange material which con-
tanned the diamonds. II any overflow
Of this eruption occurred. NO sign oft
exists now. but the overflow may have
been washed away by storms into the
valley of the vaal river and thus &C.
count for the presence Of diamonds
there. 1t is also probable that similar
mines exist elsewhere, and perhaps IN
Brazil and India they may yet be found
The foreign material forced up. a. de-
scribed, was called ''blue" BY the mixers
on account of its color, and Il now
known to consist Of . hydrous mag.
nesfan conglomerate with silica n .
base, and contains nearly all the chem
ical elements known.
Large detached boulders Of doleTite
also occur in the ''blue." which dec0m-
poses rapidly in scales ON exposure 70
the atmosphere, clearly evidencing the
action OF FIRE of great intensity.
and. as If strangely to contradict the
volcanic origin of the mines. pebbles Of
agate. plainly water worn, ara found
side by side with pieces of charred wood
and other organic matter showing the
effects of heat "a ~ :. t.' - y -
At a depth Of over three hundred feet
. section Of . tree. nearly destroyed BY
Gre. was found, the wood being Of an
unknown variety. As tho Kimberley
mine was the richest. It has been most
worked, and description Of this mine
would apply to the otheFA When FIRST
opened the mine had IN area on the
surface of about fourteen acreA and
diamonds were found only within this
area. Beyond the well defined limits Of
the mine black shale of the sub-earbon.
iferous era occurred, and as the mine
was opened to . greater depth this ma
terial fell IN and greatly hindered the
progress of mining. This shale was
called by the miners reef" This reef
continued to assume an angle of rest,
until the original surface area had been
increased to thirty acres, when . depth
of six hundred and fifty feet had been
reached Had this been. better under
stood in the first instance different
methods Of mining would have been
followed. and the mine. which .wsSi
worked or, the open quarry plan. would
have. been worked. as il II now, By opt;
side shafts and headings "st
No pen can adequately describe tie
RVOG8IO0CS % SOC Ab1U UGTbCy 0luos ~
is the largest hole made BY man ana In
The shortest space Of time. for the in-
centive to work was there-the dia-
mondL A spectator standing on the
edge looks down and sees men, looking
like ants in size, ut work, and during
the blasting hours he can in perfect
safety witness the explosion Of thou
sands of pounds Of dynamite. and note
the rending Of masses of blue and rock.
which would fall far below him. A
an honor to the late Chinese" Gordon
when he visited the mines, the writer
saw the Kimberley mine illuminated
at night with thousands Of improviaed
lamps, assisted with colored fires and
displays of fireworks The weird ef.
feet produced was grand, for the eye
could not properly measure distance 1t
might, and the twinkling lamps but
ssrvedto heighten the enect-Jewsl
erS. Weekly. s+t. -