Goo Goo Extension

Prospect, Undetermined

Alternative names

Majestic
Mother Lode

Commodities and mineralogy

Main commodities Au
Other commodities Pb; Zn
Ore minerals galena; gold; pyrite; sphalerite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale KC
Quadrangle map, 1:63,360-scale B-4
Latitude 55.3687
Longitude -131.1907
Nearby scientific data Find additional scientific data near this location
Location and accuracy
The Goo Goo Extension claim is in section 18, T. 75 S., R. 94 E., of the Copper River Meridian. It adjoins the Goo Goo claim (KC096) on the southwest. It is about 0.15 mile north of, and parallel to, Gokachin Creek, and extends from the shoreline of Thorne Arm northeastward to an elevation of about 150 feet. The coordinates at about the center of the claim. The site corresponds to loc. 94 in Elliott and others (1978), and to loc. 303 (1-16) in Maas and others (1995). The location is accurate.
Also see Additional comments.

Geologic setting

Geologic description

The Goo Goo Extension and the Goo Goo Mine (KC096) combined soon after their discovery and they share a common history. In addition, in the 1930s, both of them were sometimes linked with the Sea Level Mine (KC095). Roppel (2005) provides extensive details of the complex history of these properties. The Goo Goo vein was located in 1904 and the Goo Goo Extension in 1907, and they soon were developed by a 20-foot shaft and 15-foot tunnel. Brooks (1902, p. 67) reported gold values up to $4.00 in gold per ton (at $20.67 per ounce). About $1000 in gold (at $20.67 per ounce) was produced in 1907 from rich hand-picked samples processed with a mortar and pestle. Work continued through the 1920s and increased markedly in the 1930s with some underground exploration and considerable legal and other activity by the numerous people involved or investing in the property. Perhaps the most notable mining in the later history of the mining was the recovery in 1933 of $40,000 in gold (at $35 per ounce?) by a leaser from a rich pocket. The workings, dating back to the early 1900s, include 2 adits, one 1,800 feet long and one caved, a shaft, and several surface trenches and pits.
The rocks in the area of the Sea Level Mine are mainly phyllite and semischist derived from pelitic sedimentary rocks and andesitic or basaltic volcanic rocks, intruded by Cretaceous granodiorite (Berg and others, 1988). The premetamorphic age of the strata is speculative. On the basis of various criteria, the rocks have been interpreted as Mesozoic or late Paleozoic (Berg and others, 1988) and Permo-Triassic or Jurassic-Cretaceous (Crawford and others, 2000). The bedded rocks and some of the granodiorite were regionally metamorphosed to greenschist grade in Late Cretaceous time and subsequently remetamorphosed to hornblende hornfels near contacts of Cretaceous granodiorite plutons emplaced after the regional metamorphism. The metamorphic and intrusive rocks are overlain by Quaternary or Tertiary andesite and basalt.
Wright and Wright (1908, p. 147) describe this deposit as a 20-foot-thick quartz vein in altered schists. The vein, which they suggest is a continuation of the Goo Goo vein (KC096), strikes N63E, and contains pyrite, sphalerite, and galena. Workings in the early 1900s consisted of an open pit 10 feet deep and a tunnel 10 feet long. At that time, a picked sample assayed $30 in gold per ton (at $20.67 per ounce) (Brooks, 1902, p. 67). Maas and others (1995, p. 217) report a mean value of 959 parts per billion gold in 24 samples of the Goo Goo Extension vein. Private examination in the early-mid-1980s of an 1,837-foot adit on the Goo Goo Extension claim outlined five zones of elevated gold values, mainly along the margins of the vein(s) (Maas and others, 1995, p. 215).
Maas and others (1995, p. 216) provide the following combined description of an auriferous quartz fissure vein more than 4900 feet long on the Goo Goo claim (KC096) and its continuation southwestward onto the adjoining Goo Goo Extension claim. The vein, which strikes NE and dips steeply SE, is in mafic metavolcanic rocks and contains, in addition to free gold, pyrite, sphalerite, and galena. Hydrothermally altered metavolcanic rock adjacent to the vein contains disseminated pyrite and accompanying gold values (see Alteration). The best results of sampling in 1946 (Maas and others, 1995, p. 217) included: 5.8 parts per million (ppm) gold in a section of vein 7.5 feet thick and 79 feet long; and 7.1 ppm gold in a section of vein 4.6 feet thick and 25 feet long. Thirty-one samples of the vein collected by Maas and others (1995) contained an average of 1.1 ppm gold. Maas and others' (1995) description of the Goo Goo (KC096) and Goo Goo Extension vein indicates that its character and setting are virtually identical to the main vein on the Sea Level claim (KC095).
Combined recorded production from the claims, probably much in the early 1900s, was 1.4 kg of gold. Notably, however, $40,000 in gold (at $35 per ounce?) was produced by a leaser in 1935 from a rich pocket (Roppel, 2005).
Geologic map unit (-131.192393821014, 55.3683599730465)
Mineral deposit model Low-sulfide Au-quartz veins (Cox and Singer, 1986; model 36a).
Mineral deposit model number 36a
Age of mineralization Maas and others (1995, p. 215) note that the quartz in the veins in the Sea Level Mine area is not recrystallized; the veins thus are probably younger than most or all of the Late Cretaceous regional metamorphism.
Alteration of deposit The Goo Goo Extension vein, like most of the other principal veins in the Sea Level mine area, is bordered by a hydrothermally altered zone up to three feet thick, characterized by generally fine-grain, light-gray to bluish-gray, massive, carbonate- and sericite-bearing rock that commonly contains cubic pyrite crystals up to an inch across (Maas and others, 1995, p. 215). Maas and others (1995) interpret this zone as hydrothermally altered mafic metavolcanic rock. Early miners called this altered rock 'blue porphyry,' which they interpreted as crosscutting altered dikes that predate the quartz veins, but are closely associated with some of the orebodies (Brooks, 1902, p. 65; Wright and Wright, 1908, p. 143). Gold content of these pyritic altered zones is high adjacent to the quartz veins and diminishes away from them. Weathered altered rocks have a reddish-brown, oxidized rind up to three inches thick.

Production and reserves

Workings or exploration The Goo Goo Extension and the Goo Goo Mine (KC096) combined soon after their discovery and they share a common history. In addition, in the 1930s, both of them were sometimes linked with the Sea Level Mine (KC095). Roppel (2005) provides extensive details of the complex history of these properties. The Goo Goo vein was located in 1904 and the Goo Goo Extension in 1907, and they soon were developed by a 20-foot shaft and 15-foot tunnel. Brooks (1902, p. 67) reported gold values up to $4.00 in gold per ton (at $20.67 per ounce). About $1000 in gold (at $20.67 per ounce) was produced in 1907 from rich hand-picked samples processed with a mortar and pestle. Work continued through the 1920s and increased markedly in the 1930s with some underground exploration and considerable legal and other activity by the numerous people involved or investing in the property. Perhaps the most notable mining in the later history of the mining was the recovery in 1933 of $40,000 in gold (at $35 per ounce?) by a leaser from a rich pocket. The workings, dating back to the early 1900s, include 2 adits, one 1,800 feet long and one caved, a shaft, and several surface trenches and pits.
Indication of production Yes; small
Production notes Combined recorded production from the Goo Goo and Goo Goo Extension claims, probably most in the early 1900s, was 1.4 kg of gold (Maas and others, 1995, p. 218). Notably, however, $40,000 in gold (at $35 per ounce?) was produced by a leaser in 1935 from a rich pocket (Roppel, 2005).

Additional comments

Early reports refer to this property as the Majestic or Mother Lode claim.

References

MRDS Number A012347

References

Roppel, Patricia, 2005, Striking it rich! Gold mining in southern Southeastern Alaska: Greenwich, Connecticut, Coachlamp Productions, 286 p.
Reporters H.C. Berg (USGS); D.J. Grybeck (Port Ludlow, WA)
Last report date 3/4/2008