History
The local mining areas on the Derewo River were first discovered in 2004 by artisinal miners. The mining area lies just to the north of the Freeport COWB area which covered over 25,000km2 and has been explored from 1990 through to the present. Freeport was aware of substantial alluvial gold in the Derewo mainstream where it exits the central mountain range on to the northern coastal plain but this was not followed up. The miners followed the Derewo river, digging pits along its tributaries until they found the present mining areas in early 2004.
This area has proved extremely rich with several tonnes of gold reported having been extracted over the last few years. The 40ha mining lease held by PTMQ covers the areas furthest upstream and the most productive to date, namely Areas 81, 45 and 99 which are reported to have collectively produced in excess of four tonnes of gold since 2004.
At the time of discovery, the gold could be collected from the surface as nuggets in Area 81 although most of the gold along the river is buried under colluvial and alluvial cover. Mining of the near surface wash soon progressed to mining with underground methods. Downstream of Area 81, most of the gold has been recovered using small inefficient sluice boxes.
The volume of gravels processed each day would not exceed 10m3. Daily gold recoveries varied from 50g to over 1kg.
The miners have sunk up to 50 shafts over a 300m length of river. The most northerly yielded very little and shows the deposit does not appear to extend upstream. The tunnelling indicates it turns to the southwest.
There is very little surface gold in the river and no-one is panning the active streams.
Figure 9. Shallow surface mining and sluicing operations
