The tops and slopes of these hills (locally called Kopjes) have 
been the chief sources of diamonds to the diggers. From the 
examination of specimens made by Mr. Rupert Jones, and sent 
by Mr. Cooper, the ground appears to consist of igneous rocks 
highly felspathic, and mostly amygdaloid, which are in places 
much decomposed, and their disintegrated fragments have been 
mixed with much waterworn material of both local and distant 
origin, a point of great importance, tending to show the transport 
of material by water or it may be ice. The matrix is seen upon 
and between the crevices of the rocks, the surface being strewn 
with fragments of rocky material, viz., a metamorphic sandstone, 
quartz, amygdaloid and greenstone. The rock on which the ma¬ 
trix is found is a greenstone with a brown decomposing trap 
containing felspar, mineralogical characters going to show their 
origin to have been volcanic. Mr. Cooper tells us that the rock 
covers the whole surface. On the Kopjes it juts out in num¬ 
berless points or fragments, the whole being in detached pieces 
varying in weight from 51b. to 5001b., and in indescribable 
shapes. It does not appear to be stratified, and the detached 
fragments of which the surface is composed seem to be rather 
the result of splitting or shaling off while cooling, many sides 
presenting curved surfaces or faces, and as they are not water- 
worn, this may probably be the effect of a disintegrating process. 
These detached rock fragments reach three, four or five feet in 
depth and are removed in working and cleared away to the 
clay, which is really a decomposed felspathic amygdaloid. It 
may be remarked that the term amygdaloid is applied to any 
rock containing nodules (usually almond shaped) of some mine¬ 
rals, as agate, chalcedony, calc-spar or zeolite scattered through a 
base of basalt, greenstone, or other trap. Its origin is obvious, 
as its formation can be traced through modern lavas. Small 
pores or cells are caused by bubbles of steam or gas confined in 
the melted matrix, these spaces become gradually filled up by 
matter separating from the mass, or carried in solution by water, 
permeating the rock, and are there deposited. To resume, this 
clay forms the limit of the present workings, and is avoided by 
the diggers. The diamonds have all been found betw^een detached 
fragments of the rock (Greenstone) which occurs in irregular- 
