Griffon Mine

Producer in White Pine county in Nevada, United States with commodities Gold, Silver, Mercury, Thallium, Antimony, Barium-Barite

Geologic information

Identification information

Deposit ID	10310556
Record type	Site
Current site name	Griffon Mine
Alternate or previous names	Discover Ridge Pit, Hammer Ridge Pit

Geographic coordinates

Geographic coordinates:	-115.39894, 39.06069 (WGS84)
Elevation	1990
Relative position	The Griffon mine is located about 40 miles southwest of Ely in the east-central White Pine Range approximately 17 miles west of State Highway 6 and 30 miles south of Ely.
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Geographic areas

Country	State	County
United States	Nevada	White Pine

Public Land Survey System information

Meridian	Township	Range	Section	Fraction	State
Mount Diablo	14N	58E	24, 25, 36		Nevada

Comments on the location information

The Griffon mine is located east of the crest of the White Pine Range off the south end of Indian Garden Mountain, along the southeast end of the Cortez Trend. The mine is situated approximately 19 kilometers (12 miles) south of the Treasure Hill silver district and 13 kilometers (8 miles) east of the Green Springs gold mine.

Commodities

Commodity	Importance
Gold	Primary
Silver	Secondary
Mercury	Tertiary
Thallium	Tertiary
Antimony	Tertiary
Barium-Barite	Tertiary

Comments on the commodity information

Commodity Info: Au:Ag ratios are generally > 50:1.
Ore Materials: micron sized gold grains
Gangue Materials: hematite, limonite, opal, barite, scorodite

Materials information

Materials	Type of material
Gold	Ore
Hematite	Gangue
Limonite	Gangue
Opal	Gangue
Barite	Gangue
Scorodite	Gangue

Alteration

(Local) Mineralized 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.

Mineral occurrence model information

Model code	172
USGS model code	26a
BC deposit profile	E03
Deposit model name	Carbonate-hosted Au-Ag
Mark3 model number	15

Host and associated rocks

Host or associated

Host

Rock type

Sedimentary Rock > Clastic Sedimentary Rock > Siltstone

Rock unit name

Chainman Shale

Stratigraphic age (youngest)	Late Mississippian
Stratigraphic age (oldest)	Early Mississippian

Host or associated

Host

Rock type

Sedimentary Rock > Clastic Sedimentary Rock > Shale

Rock unit name

Chainman Shale

Stratigraphic age (youngest)	Late Mississippian
Stratigraphic age (oldest)	Early Mississippian

Host or associated

Host

Rock type

Sedimentary Rock > Carbonate > Limestone

Rock type qualifier

silty

Rock unit name

Joana Limestone

Stratigraphic age (youngest)	Early Mississippian

Nearby scientific data

(1)	-115.39894, 39.06069	ListMap

Geologic structures

Type	Description	Terms
Regional	The 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.
Local	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: (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.

Ore body information

General form Lenses and pods

General form	Lenses and pods

Controls for ore emplacement

Low-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.

Comments on the geologic information

Similar to other gold mines in the range such as Green Springs and Easy Junior, disseminated gold in the Griffon deposit occurs in strata on either side of the contact between the upper members of the Joana Limestone and overlying Chainman Formation. Low-angle normal faults are interpreted to have exerted considerable influence on the pattern of mineralization at Griffon, similar to Green Springs. Consistent with many disseminated, sediment-hosted gold deposits in the region, gold ore at Griffon contains elevated concentrations of arsenic, antimony, and mercury. However, the relatively high zinc and low silver concentrations in the Griffon ore are unusual in such gold deposits. Based on the geochemical similarities between Hammer Ridge and Discovery Ridge, a single event of gold mineralization probably formed both deposits. Age of mineralization is probably Late Cretaceous to mid-Oligocene It is unclear if the Griffon epithermal-style gold deposits are genetically linked to the Late Cretaceous intrusion-related silver and base metal deposits at Treasure Hill and Mt. Hamilton to the north.

Economic information

Economic information about the deposit and operations

Operation type	Surface
Development status	Producer
Commodity type	Both metallic and non-metallic
Deposit size	Small
Significant	Yes
Discovery year	1988
Discoverer	Billiton Minerals
Year of first production	1997
Year of last production	1999
Production years	1997-1999

Mining district

District name	White Pine District

Land status

Ownership category	National Forest
Area name	Ely District, U. S. Forest Service

Ownership information

Type Owner-Operator

Owner Alta Gold Co.

First year 1998

Last year 1999

Type	Owner-Operator
Owner	Alta Gold Co.
First year	1998
Last year	1999

Comments on the workings information

The mine was an open pit and heap leach operation, active from 1997 through1999.

Comments on other economic factors

In 1994, the geologic resource of the deposit was 50,454 oz Au in ore grading 0.039 opt Au; In 1995: proven and probable reserves.were 2.737 millon tons of ore grading 0.025 opt Au. In 1996, the resource was 2483 kilotonnes of ore containing 2.13 tonnes of gold and an unknown amount of silver. In 1997, 100,000 oz Au were produced. In 1998, projected production was 40,000 oz Au with a cash cost of production of $240/oz. gold. From 1997 through 1999, the Griffon mine produced approximately 3.0 million tons of ore with an average grade of 0.03 ounce of gold per ton.

Comments on development

Although the rich deposits of Treasure Hill and Mt.Hamilton about 10-15 miles to the northwest were known as early as 1866, the area around the Griffon deposit had no historic production or exploration activity prior to the late 1980s. Billiton Minerals first staked the Griffon property and drilled the discovery holes in1988. Subsequent drilling by Billiton and Westmont Minerals defined the Discovery Ridge deposit which by itself was not an economic deposit. After this drilling program, Griffon Resources obtained the property. In 1994, Alta Gold Company entered into a lease with option to purchase agreement with Griffon Resources. A soil sampling program conducted by Alta Gold identified the Hammer Ridge anomaly which was defined as a deposit by several phases of drilling between 1994 and 1997. Site development at Griffon began in July 1997, followed two months thereafter by the commencement of mining. Also during the 1997 program, proven and probable gold reserves at Griffon were expanded by more than 40 percent to nearly 100,000 ounces of gold. In January 1998, Alta Gold Co. announced the first gold pour from Griffon Gold Mine. Alta Gold Company operated the Griffon mine between 1997 and 1999, producing 3.0 million tons of ore with an average grade of 0.03 ounce of gold per ton. Mining was suspended at Griffon in April 1999 when Alta Gold entered into bankruptcy, but production continued in declining amounts through the end of 1999. The Forest Service collected thereclamation bond. but since it was inadequate to fully complete the reclamation work at this site, the Forest Service prioritized the reclamation and closure of the heap leach facility over the reclamation of other facilities. The site was included in a 2001 proposal to the Army Corps of Engineers by the Nevada Division of Minerals for help in reclamation and revegetation of selected Abandoned Mine Lands.

Reference information

Bibliographic references

Deposit

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.
Deposit

NBMG, 1991, The Nevada Mineral Industry 1990, NBMG Special Publication MI-1990, p.25;MI-96; MI-97
Deposit

EIS (WPG, I132)
Deposit

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.
Deposit

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.
Deposit

Alta Gold Co. press release, Jan.14, 1998.
Deposit

Elko Daily Free Press, 8/21/99.
Deposit

Alta Gold 1996 SEC Form 10K.
Deposit

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.

General comments

Subject category	Comment text
Deposit	The ore occurs in two distinct deposits, the Discovery Ridge and Hammer Ridge deposits, separated by only about 100 meters at their closest point. The center of the Discovery Ridge deposit is approximately 400 meters (1300 ft.) northwest of the center of the Hammer Ridge deposit. Both deposits are hosted by Mississippian siltstone, shale, and silty limestone (the ?Griffon Member?) that occur along the contact between the Chainman Formation and the upper Joana Limestone, which is locally interpreted to be a low-angle normal fault. The mineralized zone at Discovery Ridge is elongate, trending NNW. Thickest, highest grade material occurs in the central portion of the mineralized zone, systematically decreasing to the east, west and south. The deposit is fault-bounded to the north. Within the Hammer Ridge deposit, ore occurs in several pods and lacks the continuity of the Discovery Ridge orebody.

Subject category

Comment text

Deposit

The ore occurs in two distinct deposits, the Discovery Ridge and Hammer Ridge deposits, separated by only about 100 meters at their closest point. The center of the Discovery Ridge deposit is approximately 400 meters (1300 ft.) northwest of the center of the Hammer Ridge deposit. Both deposits are hosted by Mississippian siltstone, shale, and silty limestone (the ?Griffon Member?) that occur along the contact between the Chainman Formation and the upper Joana Limestone, which is locally interpreted to be a low-angle normal fault. The mineralized zone at Discovery Ridge is elongate, trending NNW. Thickest, highest grade material occurs in the central portion of the mineralized zone, systematically decreasing to the east, west and south. The deposit is fault-bounded to the north. Within the Hammer Ridge deposit, ore occurs in several pods and lacks the continuity of the Discovery Ridge orebody.

Reporter information

Type	Date	Name	Affiliation	Comment
Reporter	27-NOV-2000	LaPointe, D.D.	Nevada Bureau of Mines and Geology
Editor	01-SEP-2007	Schruben, Paul G.	U.S. Geological Survey	Converted from S&A FileMaker format to Oracle. Edit checks on rocks, units, and ages with Geolex search, and other fields.