Luna

Site Name

Primary: Luna

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Commodity

Primary: Copper
Secondary: Gold
Secondary: Silver
Secondary: Zinc
Secondary: Cobalt

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Location

State: Alaska
District: Koyukuk

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Land Status

Not available

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Holdings

Not available

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Workings

Not available

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Ownership

Not available

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Production

Not available

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Deposit

Record Type: Site
Operation Category: Prospect
Operation Type: Unknown
Years of Production:
Organization:
Significant:

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Physiography

Not available

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Mineral Deposit Model

Model Name: Skarn Cu
Model Name: Massive sulfide, kuroko

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Orebody

Not available

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Structure

Not available

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Alterations

Alteration Type: L
Alteration Text: Chloritic alteration of schists and silicic alteration of meta-intrusive dikes and sills.

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Rocks

Not available

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Analytical Data

Not available

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Materials

Ore: Sphalerite
Ore: Pyrrhotite
Ore: Pyrite
Ore: Magnetite
Ore: Chalcopyrite
Ore: Bornite
Ore: Arsenopyrite

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Comments

Comment (Exploration): Status = Active

Comment (Reserve-Resource): Reserves = Nicholson (1990) estimated that the deposit (including VMS and skarn mineralization) contains 2.1 million tons averaging 0.54 percent Cu, 0.17 percent Zn and 0.01 ounce of silver per ton.

Comment (Geology): Geologic Description = The Luna prospect is one of a number of copper occurrences that comprise the Chandalar copper belt. Early reports (DeYoung, 1978; Cobb and Cruz, 1983) described this prospect, together with the Hurricane-Diane property, as small deposits of skarn-hosted chalcopyrite in the Devonian Skajit Limestone intruded by a small greenstone-greenschist body. Later reports (Newberry and others, 1986) indicated they are separate prospects. Newberry and others (1986) included them in a group of skarn deposits northwest of and related to the Devonian(?) granitic plutons in the Horace Mountains. Many of these skarns exhibit both garnet and pyroxene prograde and epidote and actinolite retrograde mineral assemblages, and Newberry and others (1986) stated that their mineralogy, mineralization, and alteration of these skarns categorize them as continental-margin, porphyry-related copper skarns. Newberry and others (1986) classified the Luna deposit as a Cu-Zn-Ag skarn, and Newberry and others (1997) classify it as a calcic Cu skarn. A hand specimen of skarn from the Luna deposit contains garnet, pyroxene, epidote, actinolite, chalcopyrite, pyrite, sphalerite, and magnetite (Newberry and others, 1986). An analysis of the hand specimen gave values of 6.3 percent Cu, 32 ppm Ag, 0.57 percent Zn and 0.07 percent Pb. . More detailed descriptions (Ventures Resource Corporation, 1998) of the mineralization at Luna indicate that the primary mineral occurrence is stratabound and consists principally of chalcopyrite and lesser amounts of bornite and sphalerite in calc-silicate altered schists associated with small bodies of meta-diorite and granodiorite. Early workers (DeYoung, 1978) interpreted the occurrence as a skarn deposit. Nicholson (1990) suggested that at least parts of the mineralized package have volcanogenic affinities and noted the presence of massive, stringer, and disseminated sulfides. Mineralization also apparently occurs in 'distal' Cu-Zn skarns at Luna as well. Ventures Resource Corporation (1998) describes the deposit as including: (a) stratabound volcanogenic sulfides; (b) strata-controlled massive pyrite-chalcopyrite-magnetite skarns; (c) strata- and shear-controlled massive chalcopyrite-bornite-sphalerite replacements; and (d) a 2-foot-thick massive pyrrhotite-arsenopyrite replacement(?) in marble. Host rocks are described as chloritic calc-schist, quartz-sericite calc-schist, and skarn. Based on an extrapolation from mapping by Dillon and others (1996) a short distance south in the Chandalar C-5 quadrangle, these schist units may be Ordovician to Cambrian(?) in age. The schist units are isoclinally folded along shallow-plunging northeast-trending axes and form a broad synform which follows Roberts Creek. The Ventures Resource Corporation geologic map (1998, URL http://www.venturesresource.com/) shows meta-andesite and diorite units at the center of the sulfide occurrences. These units are in thrust contact with Devonian Skajit Limestone to the west.

Comment (Deposit): Model Number = 18b; 28a(?)

Comment (Deposit): Other Comments = See also: Hurricane-Diane (CH062), Gayle (CH091), Ginger (CH060), and Evelyn Lee (CH059).. Alaska Kardex No. 031-053 (Kardex is a card file mining claim information system located at the State of Alaska DNR Public Information Center in Fairbanks).

Comment (Workings): Workings / Exploration = The land (and the original claims) have been acquired by Doyon, Limited, an Alaska Native corporation, via its Alaska Native Claims Settlement Act selections. These Doyon lands are currently being evaluated by Ventures Resource Corporation under an agreement with Doyon. Previous work has been primarily surface exploration although five diamond drill holes, totaling 1,605 feet, were drilled in 1978. Soil sampling in 1970 to 1974 reportedly has covered less than 30 percent of the mineralized trend. Some limited trenching has also been done. Three of the five drill holes are reported to have mineralized intercepts, with one reported interval of 6 feet of 6.3 percent Cu, 0.5 percent Co, and 1.1 ounces of silver per ton (Ventures Resource Corporation, 1998). A 30 foot sample from outcrops on a 'rubble-strewn ridge' on the property is reported to assay 3.4 percent Cu, 3.1 percent Zn, 0.1 percent Co, 1.4 ounces of silver per ton and 0.014 ounce of gold per ton. Selected rock samples are reported to contain values ranging from 0.86 percent to 20.1 percent Cu, 0.19 percent to 29.2 percent Zn, 0.55 to 5.07 ounces of silver per ton, 0.01 to 0.15 ounce of gold per ton, and 0.02 to 0.41 percent Co (Ventures Resource Corporation, 1998).

Comment (Geology): Age = Devonian based on reported Early Devonian Pb/Pb zircon ages from the associated Baby Creek batholith and Horace Mountain plutons (Dillon and others, 1996).

Comment (Reference): Primary Reference = Ventures Resource Corporation, 1998

Comment (Deposit): Model Name = Cu skarn deposits; Kuroko massive sulfide(?) (Cox and Singer, 1986; models 18b and 28a)

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References

Reference (Deposit): Maas, K.M., 1987, Maps summarizing land availability for mineral exploration and development in northern Alaska, 1986: U.S. Bureau of Mines Open-File Report 10-87, 33 quadrangle overlays.

Reference (Deposit): Newberry, R.J., Allegro, G.L., Cutler, S.E., Hagen-Levelle, D.D., Adams, D.D., Nicholson, L.C., Weglarz, T.B., Bakke, A.A., Clautice, K.H., Coulter, G.A., Ford, M.J., Myers, G.L., and Szumigala, D.J., 1997, Skarn deposits of Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral Deposits of Alaska: Economic Geology Monograph 9, p. 355-395.

Reference (Deposit): Cobb, E.H., and Cruz, E.L., 1983, Summaries of data and lists of references to metallic and selected nonmetallic mineral deposits in the Chandalar quadrangle, Alaska: U.S. Geological Survey Open-File Report 83-278, 91 p.

Reference (Deposit): DeYoung, J.H., Jr., 1978, Mineral resources map of the Chandalar quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-878-B, 2 sheets, scale 1:250,000.

Reference (Deposit): Newberry, R.J., Dillon, J.T., and Adams, D.D., 1986, Regionally metamorphosed calc-silicate-hosted deposits of the Brooks Range, northern Alaska: Economic Geology, v. 81, p. 1728-1752

Reference (Deposit): Grybeck, D.J., 1977, Known mineral deposits of the Brooks Range, Alaska: US Geological Survey Open-File Report 77-166C, 41 p., 1 sheet, scale 1:1,000,000.

Reference (Deposit): Ventures Resource Corporation, 1998, 1997 Annual Report and Website (Worldwide Web URL http://www.venturesresource.com/).
URL: http://www.venturesresource.com/

Reference (Deposit): Swainbank, R.C., Clautice, K.C., and Nauman, J.L., 1998, Alaska's Mineral Industry 1997: Alaska Division of Geological and Geophysical Surveys Special Report 52, 65 p.

Reference (Deposit): Nicholson, L.M., 1990, Porphyry copper, copper skarn, and volcanogenic massive sulfide occurrences in the Chandalar copper district, Alaska: University of Alaska, Fairbanks, M.Sc. thesis, 164 p.

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