Zircons from mantle sources
are low in uranium
(generally < 66 ppm U).
Zircons and Diamonds occur
in a variety of mantle rocks.
Zircons are very resistant
to weathering and persist in drainage systems.
The presence of low uranium
zircons in stream samples and other recent sediments can therefore
indicate derivation of material from potential diamondiferous
Zircons can be easily extracted
from bulk samples with standard mineral separation techniques.
The Fission Track Technique
is a low cost, rapid turnaround method for determining uranium
content of individual zircon grains with a precision of ~10%
at the 10 ppm level).
Large numbers of grains can
be screened quickly and cheaply to identify the presence of
low uranium zircon grains.