The Fifield District was Australia’s largest dedicated Platinum producer. Platinum group metals and alloys together with gold were first discovered in the Fifield District in 1880’s, and are reported to have been produced from three alluvial leads (paleochannels), namely the Gillenbine, Fifield and Platina leads. The Platina lead is the largest of these at 3km strike length and 10m~25m deep.
The deposits were shallow and worked by surface mining with the ore material being first collected by horse drawn scoops. Deeper deposits were worked by underground selective hand mining. The usual method of treatment was to puddle the wash in puddling machines operated by horse or steam power, then to pass the de-slimed material through sluice boxes. The sluice box concentrates were further concentrated by hand panning and the gold was separated from the platinum by amalgamation with mercury.
The Fifield alluvial platinum deposits have recorded production of 650 kg (20,000 Oz) of platinum since the 1880’s and 6,200Oz of gold. Analysis of the platinum indicate a mixture of platinum (~75 –80%), iridium, rhodium, palladium, osmiridium (~5-9 %) and iron (~10%). The Platina Lead was the main target for historical miners with the majority of the shaft dumps still present (686 identified and mapped by Rimfire to date).
Historical mining techniques, a lack of water, and limited processing technology meant that a high grade was required for viability of historical operations. The reported historic head grade in the Platina Lead was around 15 g/t platinum grade.
Despite the early mining history drawing a significant population of prospectors and miners from the 1880’s, the Fifield District has seen very limited modern exploration, quite remarkable given the geological setting and underlying prospectivity of the region.