Description
Billiton Minerals
Commodities
PrimaryGold
SecondarySilver
TertiaryBarium-Barite, Antimony, Thallium, Mercury
Commodity typeB
Deposit
Deposit typeAlligator-type
Model172: Carbonate-hosted Au-Ag
Deposit sizeS
Orebody formLenses and pods
Ore controlLow-angle normal faults are interpreted to have exerted considerable influence on the pattern of mineralization at Griffon. Both the Discovery Ridge and Hammer Ridge deposits are composed of mineralized strata situated in the hanging-walls of these faults.
Materials
Ore mineralsGold
GangueHematite, Limonite, Opal, Barite, Scorodite
Geology
Host rockSiltstone,Shale,Limestone · "Chainman Shale", "Joana Limestone"
StructureThe structural geology of the Griffon property includes Mesozoic contractional structures with superimposed Cenozoic extensional structures that have locally obscured, rotated, or reactivated older structures. The White Pine Range falls within the Central Nevada Thrust Belt,a zone of pre-early Cretaceous contractional structures in rocks as young as Permian. Regional structures include low amplitude, open folds with axes that strike between N-S and N15E., The Griffon property has been subjected to multiple episodes of deformation predating, concurrent with, and post-dating mineralization. The proposed sequence of deformational events at Griffon is:\n(1) Early high-angle normal faulting striking roughly WNW that offsets Devonian through Mississippian rocks up to 55 meters (180 ft.). (2) Upright, open folds trending N to NNE with possible thrust faulting. (3) Low-angle normal faulting which is most likely associated with the mineralizing event, since mineralized strata in the hanging-wall of this fault comprise both the Discovery Ridge and Hammer Ridge deposits. (4) Several episodes of high-angle normal faulting and possible strike-slip faulting that commonly offset mineralized strata. (5) Later movement along the Blackrock fault, a major low-angle normal fault of probable Oligocene age in the southern part of the range. At Griffon, the Blackrock Fault moved after gold mineralization had occurred and is interpreted to have been active between 31.3 and 14.3 Ma. \n
Tectonic settingCentral Nevada Thrust Belt
AlterationMineralized strata are variably altered with local argillization, silicification, decalcification, and jasperization. There is, however, no direct correlation between ore grade and alteration. Despite the prominent role of jasperoid in the discovery of the deposit, very little of the actual ore is strongly silicified. \n
Economic & production
Development statusProducer
Production years1997-1999
First production1997
Last production1999
Discovery year1988
Identification
Deposit ID10310556
Alternate namesDiscover Ridge Pit, Hammer Ridge Pit
RegionNA
Data scoreB
Coordinates39.06069, -115.39894
References
Carden, J.R., 1991, The discovery and geology of the Nighthawk Ridge deposit at Easy Junior, White Pine County, Nevada, in Geology and Ore Deposits of the Great Basin, Raines, G.L., Et Al, Eds., The Geological Society Of Nevada, Reno, p. 665-676.NBMG, 1991, The Nevada Mineral Industry 1990, NBMG Special Publication MI-1990, p.25;MI-96; MI-97EIS (WPG, I132)Long, K.R., DeYoung, J.H., Jr., and Ludington, S.D., 1998, Database of significant deposits of gold, silver, copper, lead, and zinc in the United States; Part A, Database description and analysis; part B, Digital database: U.S. Geological Survey Open-File Report 98-206, 33 p., one 3.5 inch diskette.Robinson, J.P., 2000, The Griffon Mine: Contraction, Extension, and Gold Mineralization in the White Pine Range, Nevada, in Geology and Ore Deposits 2000: The Great Basin and Beyond Proceedings, Editors, J.K. Cluer, J.G. Price, E.M. Struhsacker, R.F. Hardyman, and C.L. Morris, p. 1157-1171.Alta Gold Co. press release, Jan.14, 1998.Elko Daily Free Press, 8/21/99.Alta Gold 1996 SEC Form 10K.Nevada Division of Minerals, 1/26/2001,Proposal to the Army Corps of Engineers for help in reclamation and revegetation of 11 selected Abandoned Mine Lands in Nevada.