44 THE MATRIX OF THE DIAMOND
well
as those of Brewster, Petzhold, Wohler and Desclois-eaux, Sorby and
Butler, Damour and Dumas can only here be mentioned. The supposed
discovery by Goeppert' of plants and organic cells in the diamond has
not yet been verified.
The
explorations of the last few years have placed it beyond question that
the serpentine rock called ' blue ground' is in reality the matrix of
the diamond. For a time it was thought that the diamonds were washed
into the ' kopjes ' from above, being mere alluvial deposits, as held
by Mr. Cooper 2 and others; afterwards, and until the
present time, the idea has been general that they were carried up from
below along with other inclusions, and that their true matrix was some
gneiss or itacolumite far below, from which they had become detached by
volcanic agency. Others again, such as Doll,3 hold that
while the serpentinous rock is the matrix of the diamond, the latter is
a secondary mineral due to the decomposition of the rock.
But
recent investigations seem to place it beyond quesÂtion that diamonds
are as much a part of the Kimberley rock as biotite, garnet, titanic
and chromic iron and perovs-kite, and that, like these minerals, they
may be considered as a rock ingredient. The fact that they continue
just as abunÂdant, if not more so, the deeper the mines are explored:
that they are never found in, or especially associated with, the
foreign inclusions of gneiss, granite, or sandstone : that they are
distributed abundantly through all parts of the rock : and that in each
of the four principal mines the diamonds have distinctive features of
colour, lustre, and shape, are, with the microscopical evidence of the
eruptive
