The Portland daily press., 1898-09-16
DIAMONDS IN SOUTH AFRICA.
Some characteristics About the Earth in
the Mines.

Regarding any reported discovery of
new diamond mine, one of the first
questions asked is, SIS it pipe?" because
il SO there is every reason to be assured
of it's permanency. Those pipes are
throughly circular or elliptical in section,
and several hundred feet, sometimes 1000
feet, across. Contrary to the once COM
mon belief, there is very seldom a basin
like depression or other change in the sur
face topography to indicate their ex-
istence.
The ground forming the top of the
"pipe' is, for about the first thirty yards
in depth, usually of a light yellow color,
due to the decomposition of the "KimDer-
lite'' or diamondiferous rock, and is
called yellow ground" "Blue ground, -
in which the Kimberly and De Beers
mines have been working for years past,
is the hard, unoxidized and unhydrated
diamond bearing rock of the general tone
of color indicated by its name. 1t re-
quires drilling and blasting like any
other hard rock, but the impression
broken is erroneous. The fracture is
more often due to passage through the
fine rolls in the washing operations rather
than to blasting. Upon exposure to all
this rock changes to a gray color, and
disintegrates and crumbles, especially
after moietening with water.
10 this fortunate characteristic is due
the existence of the extensive floors
at Kimberly, containing millions of tons
Of blue ground In all degrees of weather.
ing.
The floors are divided up into sspaces,
400 yards by 900 yards, and on these the
blue ground is deposited for depth of
to which the fiat "veldt'', or prairie land,
is subjected previous to receiving the
"Kimberlite, is to be stripped of grass,
bush and any loose stones. Formerly it
Yves rolled hard and smooth, but this is
not now done.
The first operation the Kimberlite un-
dergoes is that of narrowing, the harrows
being drawn back and forth between 1.-TWO
traction engines, stationed several hun
dred yards apart, thus avoiding the pack
ing that would take place II the blue
ground were travelled over by a steam
ha rrow. After proper interval, the next
process is that of winnowing, or collect
Ing the Jumps Of hard blue" that will
not disintegrate into heaps. Portable
tracks are laid down and tbs Jumps are
sent to the crusher house.
A second narrowing then takes place,
and if no rains have set in, the deposited
ground is wet by hoes a complete system
of water pipe being laid over the floors"
for the purpose.
After another interval, to allow of fur.
ther weathering taking place, the ma
terial Is loaded into cars on movable
tracks, run to the main heulage and sent
to the washing machines, any remaining
piece of hard "plue' being stacked sepa-
rately and sent to the crushing and con-
oentrating mill. The floor is then ready
for q fresh deposit from the mines.
The entire cycle of operations takes
about year for the DeBeers blue ground ;
sometimes less than this when rains are
more frequent The Kimberly blue
ground dIsintegrates in half that time.
The floors are fenced about with barbed
wire fencing, and are continuity under
guard, the night watch being aided by a
system of wali.arranged arc lights.
On July 1, 1897, there were lying upon
the depositing floors;of the Kimberly ,
De Beers, and the newly-started Vessel
ton mine an amount of 2, 576,634 loads OF
! diamond rock, equal to 2,06l, S55 tons.
| At moderate estimate this tonnage CON-
taius over e3, ,000 600. worth of diamonds
and it ahso represents very iarge-smount
of capital invested in the mining and
transportation of the material. .-Cassiep' 8
Magazine.