Gold and platinum placer occurrences found in the Finlay, Parsnip and Peace rivers have been worked since the first discovery by Bill Cust in 1861. The placers generally occur in the top 1.5 to 3 metres of reworked glacial gravels deposited in streams and as benches along streams. Normally worked by hand, these placer operations had limited success. The gold is fine and flat and platinum is common with local high values reported, but it was considered unimportant in most of these placers.

Rainbow Creek, a tributary of the Nation River flows north through the Manson Upland, approximately 60 kilometres south of the town of Mackenzie. Discovery of gold in Rainbow Creek, 2 to 3 kilometres above its confluence with the Nation River, in 1929, led to over 40 kilometres of the Creek being staked and worked by 1931. The fine grained nature of the gold and the low platinum content meant many showings were not profitable. Between 1931 and 1935, 1431 grams of gold were recovered from Rainbow Creek. No other accurate production records are available. Iridium values have also been obtained from assays.