General History of the Nine Mile Mining District
The first gold discoveries were made in the district in 1874 (Lyden, 1948, p.103-104). Some of the deposits were rich and several miles of placer ground were quickly located, some of which were patented. The amount of gold mined in the district prior to 1908 has not been ascertained but is reported to have been several million dollars (Lyden, 1948, p.103-104). Placer operations along the creek were sustained for many years, but production declined sharply after 1915 and was intermittent in the 1920’s. The pace of mining increased in the 1930’s and, except for the war years of 1943-45, continued at a significant level through 1948. In 1954 dredging operations recovered 1,340 ounces of gold; otherwise the district has been mainly idle from 1949 through to the present. Total production for the district was thought to be between 100,000 and 125,000 ounces, nearly all being placer gold.
Nine Mile Mining District Geology
The gold deposits of the Nine Mile District lie within the area which has been mapped by the United States geological survey as undifferentiated Belt series comprising a great thickness of tilted folded and faulted Algonqian rocks chiefly sandstone and shale and their slightly altered equivalents. It is the basic equivalent of the Coeur d’ Alene district’s Prichard, Burke, Revett, and St. Regis formations.
Covering the bedrock throughout the region is a surface mantle of mingled clay and gravel. The general topographical features suggest its origin as being a ground moraine. This is seen on the ground as a sub-glacial or ice-laid deposits of till. The gravel ranges from 8 to 20 feet in thickness, averaging about 15 feet. The gravel boulders range up to a foot and a half in diameter. The matrix is typically a brownish and bluish boulder clay. The glacial material was derived from the uplands and mountains of the Northeast, scoured off the surface by the ice sheet, shoved or drug down the slopes, crushed, ground, and finally compressed beneath the ice sheet mass into its present condition. The source of the gold is probably the scattered gold veins in the mountains at the head of the creeks (Pardee, 1918, P. 234). The ice sheet probably covered the basin with a thickness of 1000 feet or more for a period of centuries.
The gold is quite pure and has been stated to be at 980 fine in some areas of the district. It consists mainly of fine flakes to coarse nuggets in excess of 10 ounces. The gold is concentrated within a foot or so of the bedrock. In the 1940’s a dredge was assembled and successfully operated in the Nine Mile Creek drainage along the southern flank of this property. It was stated in The Gold Districts of the United States that in 1946, this dredge produced 2,276 fine ounces of gold during the one placer season.
The potential for the Nine Mile district is still for the most part unrealized, “It may be stated that after deducting more than half of the volume of the gravel sheet for postglacial stream erosion and bedrock wastage, and making due allowance for the fact that most of the gravels hitherto worked were probably secondary, as in the earlier workings on Kennedy Creek, in which concentration of the gold had taken place by glacial and recent streams, by rough estimate the district probably contains about $100 million worth of gold.” (Calkins, F.C., a geological reconnaissance in northern Idaho and northwest Montana: Bull, U.S., Geol. Survey No.384, 1909, p.77.). This would translate to $5 billion at today’s prices for the estimated gold still contained in the Nine Mile Mining District.