Double Anchor; Alaska State Mines Extension Prospect, Hyder Mining District, Prince of Wales-Hyder Census Area, Alaska, USAi

Regional Level Types
Double Anchor; Alaska State Mines Extension Prospect	Prospect
Hyder Mining District	Mining District
Prince of Wales-Hyder Census Area	Census Area
Alaska	State
USA	Country

Four claims were recorded in 1923; property was restaked in 1958 as part of the Alaska State Mines Extension claim group of 19 lode and 2 placer claims. The claims were inactive in 1973 (Berg and others, 1977, p. 76).
Location: The Double Anchor prospect is in Section 16 at an elevation of about 4100 feet near the top of a south-facing mountainside overlooking Texas Lake, about 0.7 mile south of the lake (Berg and others, 1977, p. 79; Elliott and Koch, 1981, p. 11, loc. 30).
Geology: The country rocks in the area near the Double Anchor prospect are pelitic metasedimentary and minor andesitic metavolcanic strata of the Jurassic or older Mesozoic Hazelton Group; the Triassic Texas Creek Granodiorite, which underlies and locally intrudes the Hazelton; and the Eocene Hyder Quartz Monzonite, which cuts both the Hazelton and Texas Creek rocks (Smith, 1977; Koch, 1996). Buddington (1929, p. p. 98-99) describes the deposit as a subhorizontal shear zone in argillite and graywacke that contains seams and stringers of quartz and sulfides, including sphalerite, galena, pyrite, chalcopyrite, and sparse pyrrhotite. The largest orebody is about 2.5 feet thick and 30 feet long; most individual veins are less than an inch thick. Thick quartz veins nearby are only sparsely mineralized. Berg and others (1977, p. 38-39) describe two quartz breccia zones. One is subhorizontal, up to about a foot thick, and exposed for about 700 feet along strike; the other dips steeply and is exposed for about 160 feet along strike. Both zones contain pyrite, galena, sphalerite, and chalcopyrite. The weighted average of analyses of samples collected by the U.S. Bureau of Mines in 1972 (Berg and others, 1977, p. 79-84) across about a two-foot-width of the main (subhorizontal) orebody is 4.3% Pb, 1.0% Zn, and 3.5 oz Ag and 0.022 oz Au per ton. Lead-isotope studies of galena from the Double Anchor prospect have yielded Jurassic and Eocene ages (Maas and others, 1995, p. 235, 244). The deposit is interpreted to be polygenetic, originating during Jurassic Hazelton island-arc volcanism (Alldrick, 1993), and then partly remobilized or reconstituted as fissure veins during Eocene emplacement of the Hyder Quartz Monzonite.
Workings: Prospect was explored, probably in the 1920's, by pits and short adits. The weighted average of analyses of samples collected by the U.S. Bureau of Mines in 1972 (Berg and others, 1977, p. 79-84) across about a two-foot-width of the main (subhorizontal) orebody is 4.3% Pb, 1.0% Zn, and 3.5 oz Ag and 0.022 oz AU per ton.
Age: Lead-isotope studies of galena from the Double Anchor prospect have yielded Jurassic and Eocene ages (Maas and others, 1995, p. 235, 244). The deposit is interpreted to be polygenetic, originating during Jurassic Hazelton island-arc volcanism (Alldrick, 1993), and then partly remobilized or reconstituted during Eocene emplacement of the Hyder Quartz Monzonite.
Alteration: Local intense iron staining. The subhorizontal quartz breccia zone is oxidized.

Commodities (Major) - Ag, Au, Cu, Pb, Zn; (Minor) - Cu
Development Status: None
Deposit Model: Polymetallic veins

Other Databases

Link to USGS - Alaska:	BC030

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References