THE INTERPRETATION OF THE MAJOR ELEMENT
COMPOSITIONS OF MANTLE MINERALS IN DIAMOND
EXPLORATION
J.J. Gurney1 and P. Zweistra2
1
Dept. of Geological Sciences, University of Cape Town, Rondebosch 7700, South Africa
2
Scientific Services, P.O. Box 527, Howard Place 7450, South Africa
ABSTRACT
Interpretation of the major element compositions of the mantle macrocryst
minerals recovered during stream sediment or soil sampling should be one of the
corner-stones of any modern exploration programme for diamonds. Studies must
be implemented in such a way as to elucidate the maximum information about
the lithospheric mantle underlying the exploration area of interest. This can
provide a qualitative or at best semi-quantitative estimate of diamond potential.
The composition of a suite of peridotitic garnets from a region or locality is
particularly
useful
in
differentiating
between
diamond
bearing
and
non-
diamondiferous mantle samples. Assessments of macrocryst composition are a
means of prioritising exploration efforts useful over an extensive period of an
active exploration programme, and in a variety of different sets of circumstances.
Differences in mantle mineral suite compositions may also be used to identify and
isolate specific exploration targets for further attention in areas where numerous
potential diamond sources exist.