Bird's Beak

Prospect, Active

Alternative names

Bird Beak

Commodities and mineralogy

Main commodities Ni; Pd; Pt
Other commodities Au; Cr; Cu
Ore minerals chalcopyrite; chromite; magnetite; moncheite; pentlandite; pyrrhotite

Geographic location

Quadrangle map, 1:250,000-scale MH
Quadrangle map, 1:63,360-scale B-5
Latitude 63.3174
Longitude -146.3966
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Bird Beak prospect is at an elevation of about 5,900 feet, about 1,600 feet southwest of peak 6120 and about 0.8 mile west of lower Eureka Glacier. It is in about 0.7 mile northwest of the center of section 34, T. 18 S., R. 7 E., of the Fairbanks Meridian. Bittenbender and others (2007, figure 14) show an aerial view of the prospect.

Geologic setting

Geologic description

The Bird Beak prospect is in an Upper Triassic ultramafic and mafic sill-like complex in fault contact with a Tertiary to Cretaceous composite granitic to dioritic pluton (Nokleberg and others, 1991). Rose (1966) mapped dunite bodies associated with diorite, quartz diorite, and gabbro in this area. Mafic and ultramafic rocks in the Broxson Gulch thrust may have lubricated the footwall of the thrust (Kurtak and others, 1992). The hanging wall of the thrust consists of schist. Olivine metagabbro and serpentinized dunite host the ore minerals at the prospect.
The U.S. Bureau of Mines collected samples of dunite and gabbro from the prospect (Kurtak and others, 1992). Sample 3038 of olivine gabbro with disseminated pyrrhotite and chalcopyrite assayed 0.15 percent copper, 0.21 percent chromium, 0.36 percent nickel, 550 parts per billion (ppb) palladium, and 80 ppb platinum. Sample 2644 of limonite-stained serpentine contained 0.13 percent copper, 896 parts per million (ppm) nickel, 280 ppb palladium, and 570 ppb platinum. A pentlandite(?)-bearing pyroxenite sample assayed 0.2 percent nickel and 25 ppb platinum.
Foley (1992) reported similar values in red, iron-oxide-stained, sulfide-rich, olivine gabbro; microprobe examination of the gabbro showed minute particles of moncheite (PtTe) along grain boundaries between chalcopyrite and ferromagnesian silicate minerals.
Bittenbender and others (2007) sampled the prospect. Their best samples were from a gabbro sill that cuts peridotite. Two selected samples contained up to 167 ppm gold, 462 ppb platinum, 385 ppb palladium, 1,820 ppm copper, and 4,450 ppm nickel. A more representative sample of approximately a 10 by 10 foot area of the gabbro contained 34 ppb gold, 105 ppb platinum, 94 ppb palladium, 592 ppm copper, and 1,815 ppm nickel. They indicate that the mineralization is well exposed but is unlikely to be of significant size.
In 2001, the prospect was on claims of the MAN project of Pure Nickel Inc. Pure Nickel sampled the Bird's Beak showing in 2011 and grab samples returned values of 1.39 percent nickel, 0.48 percent copper, and 7.0 grams of platinum group elements + gold + silver per tonne (Pure Nickel Inc., 2011).
Geologic map unit (-146.398866482896, 63.3169743826383)
Mineral deposit model Nickel-copper-PGE mineralization in a differentiated mafic-ultramafic complex.
Age of mineralization Probably Late Triassic; synchronous with emplacement of the mafic-ultramafic complex (Nokleberg and others, 1991).
Alteration of deposit All of the ultramafic rock units are moderately to strongly serpentinized (Bittenbender and others, 2007).

Production and reserves

Workings or exploration
The prospect was sampled by the U.S. Bureau of Mines (Kurtak and others, 1992) and the Bureau of Land Management (Bittenbender and others, 2007).
In 2001, the prospect was on claims of the MAN project of Pure Nickel Inc. Pure Nickel sampled the Bird's Beak showing in 2011 and grab samples returned values of 1.39 percent nickel, 0.48 percent copper, and 7.0 grams of platinum group elements + gold + silver per tonne (Pure Nickel Inc., 2011).
Indication of production None
Reserve estimates None.
Production notes None.

References

References

Reporters W.T. Ellis (Alaska Earth Sciences), C.C. Hawley (Hawley Resource Group); W.J. Nokleberg (USGS); D.J. Grybeck (Contractor, USGS); V.C. Zinno (Alaska Earth Sciences, Inc.)
Last report date 12/10/2014