Multiple syngenetic metalliferous horizons enriched in V, As, Mo, Se, Ni, Ag, Zn and Au in the Northern Carlin Trend: Implications for the genesis of world class gold-arsenic deposits


In 2008, Idaho’s non-fuel mineral production is estimated to have a record value of
$ 1.1 billion, even with the downturn in commodity prices in the final quarter.Molybdenum
is the state’s highest value commodity, followed by phosphate rock, construction
sand and gravel, and silver. Base metals and other industrial minerals are also important
products. In the boom of the first half of 2008, the largeThompson Creek molybdenummine
and Hecla’sLucky Friday silver mine were planning expansions.U.S. Silver’s
Galena mine had an ambitious exploration/development program and the Sunshine silvermine
had reopened and then closed. Expansions have been slowed by the recession,
but not forgotten as prices stabilized in mid-2009. In addition, two new mine plans have
been approved by regulatory agencies, though construction was delayed. The Forest
Service denied the appeal of another mining company and upheld the Record of Decision
and mine plan for Formation Capital Corporation’s Idaho Cobalt Project. Formation
Capital negotiated agreements with environmental groups to help mitigate their
concerns, and by September 2009, had received all needed environmental permits and
court award of access across the Blackbird Mine Site. The new underground, copper-
cobalt-gold mine in the Blackbird Mining District of Lemhi County will produce an
estimated 1500 tons per year of high purity cobalt metal from the mine and its
hydrometallurgical facility inKellogg. Formation Capital’s discovery, the Ram deposit,
like other deposits in the district, has been interpreted as a Proterozoic-age syngenetic,
rift-related exhalative deposit, which has been folded, faulted and locally remobilized
during Mesozoic deformation. However, recent studies published on the African Copper
Belt, coupled with extremely radiogenic lead isotopic ratios at Blackbird, suggest alternate
mechanisms involving basinal brines may also have had a role in the primary
mineralization. The ten-year mine life should be supplemented by the excellent exploration
potential in the district.

SKU: 2010-01 Category:

Additional information


Primary Author

Ross Large





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Deposit Type



Geologic Era