6/9/2004

An area which has kept our Harare laboratory busy for many months now is that of concentration of soil samples for geochemical exploration. The samples, derived from a primary exploration program by a Zimbabwean company which must remain nameless, are concentrated down to about 10 g from starting masses of about 8kg concentration ratios of over 500/1.

Enhanced gravity concentration is used in order to capture any high-density constituents from the scrubbed and dispersed soil samples. Gravity concentrates are then analysed overseas for a variety of elements. Unlike BLEG leaching, which targets only gold anomalies in soil sampling programs, this method reveals anomalies of any heavy mineral or metal, from chromite through base and precious metals to radioactive elements, and even diamond tracer minerals.

The relatively simple methods employed for scrubbing and primary concentration allow for high volume throughput at low cost. To date Peacocke & Simpson has processed well over 10 000 samples by this method, with throughput of up to 2 000 samples per month. The numerous mineral anomalies which have been revealed in the exploration program are exciting to say the least.