THE GREAT KIMBERLEY DIAMOND MINE. 
97 
now have a good chance of sharing in the most valuable 
portion of the mine, the “ Blue ” stuff, on account of the 
general inclination towards the right hand of the great 
“ pipe” comprising the entire deposit; when the time comes 
that the general excavation of the pit reaches the required 
depth, as illustrated by the vertical dotted line (e) on the right 
of the section, Fig. 2. The claims situated on the left of the 
original field have lost from this cause all further chance, 
after sharing in the top yellow stuff. 
The great “pipe” forming this mine is looked upon as 
probably the throat of an ancient volcano, of which the 
summit cone has been removed by denudation, and the throat 
has remained filled up with volcanic mud and other material 
forced up from below, amongst which the diamonds are 
distributed ; and this consideration suggests the possibility of 
an increased yield of diamonds being found as the workings are 
carried still deeper. To effect this, however, it will be requisite 
to have recourse probably to sinking shafts, with regular under¬ 
ground mining work, the practical limit of “ open working” 
having been now nearly reached. The diamonds found are 
either perfectly pure or more or less coloured, and also the 
black diamonds called “ bort,” and, as found imbedded in the 
material of the “ pipe,” they generally show evidence of 
having been exposed to some severe disturbing force, their 
angles being frequently abraded, and many being fragments 
fractured from larger stones. One form of the diamonds is 
known as “ splints,” consisting of thin plates. 
The other three diamond mines adjoining the Kimberley 
mine and the two in Orange Free State are also of a similar 
character in natural formation ; but the river diggings are of 
an entirely different character, and the diamonds that are 
there found in superficial gravel deposits are looked upon as 
possibly derived from uplieaved volcanic material in a higher 
district of the country that has been denuded and carried 
down by water action. The diamond fields in other parts of 
the world are also generally of this latter character, and the 
diamond mines of the Kimberley district are quite unique in 
their character, and of special interest as affording some 
important information towards a knowledge of the source of 
origin of the diamond. Several other “pipes” have been 
opened and partially worked in the Kimberley district, but 
were subsequently abandoned as unremunerative, although 
some diamonds were obtained ; probably by deeper sinking 
richer yields would have been found. 
The Kimberley mines are situated at an elevation of about 
4,000ft. above the sea, and the range of mountains, the 
