Agostino

Site Name

Primary: Agostino
Secondary: Barnes Property
Secondary: Monarch Mining Co.
Secondary: Crow Creek Mining Co.

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Commodity

Primary: Gold
Secondary: Molybdenum
Secondary: Lead
Secondary: Copper
Secondary: Silver
Secondary: Zinc

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Location

State: Alaska
District: Anchorage

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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: Past Producer
Operation Type: Unknown
Years of Production:
Organization:
Significant:

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Physiography

Not available

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Mineral Deposit Model

Model Name: Low-sulfide Au-quartz vein, Chugach-type

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Orebody

Not available

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Structure

Not available

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Alterations

Alteration Type: L
Alteration Text: The intrusive rocks have undergone argillic alteration. Some galena has been altered to cerussite (Johnson, 1912). Limonite and abundant scorodite is also present where arsenopyrite is prominent (Hoekzema and other, 1987).

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Rocks

Not available

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Analytical Data

Not available

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Materials

Ore: Silver
Ore: Molybdenite
Ore: Gold
Ore: Chalcopyrite
Ore: Arsenopyrite
Ore: Sphalerite
Ore: Silver
Ore: Pyrrhotite
Ore: Galena
Ore: Pyrite
Gangue: Quartz
Gangue: Calcite

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Comments

Comment (Geology): Age = Tertiary or younger

Comment (Exploration): Status = Inactive

Comment (Deposit): Other Comments = There is some confusion in literature distinguishing between this property and the Jewel mine, which apparently was connected to Agostino mill at one time. Both were probably under the same management (Crow Creek Mining Co.) during the 1930's.

Comment (Geology): Geologic Description = Park (1933) decribed the geology: Two quartz veins (called the North vein and the South vein by the owners) cut Late Cretaceous age metasedimentary rocks of the Valdez Group which are intruded by many dikes and small, irregular shaped intrusive bodies of holocrystalline argillically altered quartz diorite. Locally, the bedded rocks strike nearly west and dip 40 N. The country rock has been badly shattered near the veins, and part of the deformation is postmineral, resulting in brecciated vein materials, which in some places have been recemented and again fractured. Both the North and the South veins are traceable for several hundred feet along strike. The South quartz vein ranges in width from 6 inches to about 4 feet, with an average of 9 inches in the tunnel. The strike is from east to S 80 E, and the dip is 55 to 70 N. Many fragments of country rock are isolated in the quartz. The North quartz vein strikes N 80 E, and dips about 70 N. Where exposed in the tunnel and in several surface cuts it is from 10 inches to 3 feet wide, with an average of 1 foot. The North vein appears to be somewhat better defined than the South vein and may be traced farther on the surface. There are several crosscutting veins 6 inches wide that strike a few degrees west of north and dip either east or west. The North vein offsets these small veins. The crosscutting veins of this north-south system are very persistent and one mineralized vein 6 to 8 inches wide was followed for more than 500 feet. The mineralization includes at least two generations of quartz, small amounts of calcite, galena, arsenopyrite, sphalerite, chalcopyrite, pyrrhotite, molybdenite, pyrite, gold, and silver. The silver occurs alloyed with gold (75 percent Au, 25 percent Ag). When not with gold, the silver seems to be associated with galena. Considerable magnetite is found in the concentrates obtained by panning.? A random samples of molybdenum-bearing cross-vein contained 0.26 percent Mo (Park, 1933). Samples taken by the Bureau of Mines contained up to 234 ppm Au and 92 ppm Ag (Hoekzema and others, 1987). Jansons and others (1984) report 43 chip and grab samples contained from a trace to 6.82 oz/ton Au, trace to 3.94 oz/ton Ag, up to 400 ppm Mo, and 1.34 percent As. Weighted average grade of all chip samples is 0.31 oz/ton Au and 0.31 oz/ton Ag.

Comment (Production): Production Notes = Total recorded production, including that of the Jewel Mine (ARDF number AN107), was 4,932 oz gold and 996 oz silver (Hoekzema and others, 1987).

Comment (Reference): Primary Reference = Park, 1933

Comment (Workings): Workings / Exploration = Berg and Cobb (1967) indicated the Agostino Mine was the site of the most extensive development in the Girdwood area. The site was discovered by Conrad Hores in 1909 and prospected or mined (with interruptions) until as recently as 1941. Johnson (1912) reports that development began in 1910. In 1910-11 there were about 675 feet of underground workings on three levels and some open cuts. Owners reported that the free milling ore from main veins averaged $35 to $40 per ton (gold at $20.67/ton), with much higher assays from single samples. Wall rocks were said to not be gold-bearing. After 1911, Brooks (1922) reported plans for some work in 1920 and Smith (1929) reported plans for adding machinery in 1926. Minor production occurred in 1926 and 1928 using a 1-stamp mill, small crusher, and amalgamation plate. Park (1933) indicated the group of claims was originally known as the Barnes property and has changed owners several times. The Monarch Mining Co obtained control several years prior to 1933. This company was taken over by the Crow Creek Mining Co., Inc. which gave a lease and option to the Bruno Agostino Mining Co. - controlled and operated by four men in partnership. The last group pushed development vigorously during 1931, installing a larger mill that utilized hydropower and three 1,200-foot tram lines (Hoekzema and others, 1987). Development of the property, 1933, included opening two parallel veins, called by the owners the North and South veins. There is one adit 260 feet long on the North vein and one 267 feet long on the South vein. In addition, there are two crosscutting adits, one containing 295 feet of workings and the other 60 feet. A lower adit, planned to crosscut the workings in depth, has been driven 190 feet. A winze on the South vein was open for 40 feet and was reported to be 10 feet deeper but filled with debris. There was also a 10-foot winze on the South vein. The total workings is 1,072 feet and the winze length more than 50 feet (Park, 1933). Production continued from 1933 until 1941. Roehm (1937) reported that development in 1937 consisted of 950 feet of drift, 125 feet of crosscuts, 52 feet of winze, and 4 raises totaling 100 feet. Two levels at elevations of 3,200 ft and 3,300 ft developed the South vein. The North vein was developed on two levels at elevations of 3,285 ft and 3,420 ft. A 60-ft-long adit was developed 500 feet north of the North vein at an elevation of 3,500 ft to examine a north-striking molybdenum-chalcopyrite-bearing vein. Most of the stoping and production appears to have come from the upper level of the south vein.? A random sample of molybdenum-bearing cross-vein contained 0.26 percent Mo (Park, 1933). Samples taken by the Bureau of Mines (Hoekzema and others, 1987) contained up to 234 ppm Au and 92 ppm Ag. Jansons and others (1984) report 43 chip and grab samples contained from a trace to 6.82 oz/ton Au, trace to 3.94 oz/ton Ag, up to 400 ppm Mo, and 1.34 percent As. Weighted average grade of all chip samples is 0.31 oz/ton Au and 0.31 oz/ton Ag. This deposit has high mineral development potential for a small mine, based on history and sampling, if vein extension can be located (Jansons and others, 1984).

Comment (Commodity): Ore Material = argentiferous galena

Comment (Deposit): Model Name = Chugach-type low-sulfide Au-quartz veins (Bliss, 1992; model 36a.1)

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References

Reference (Deposit): Smith, P.S., 1930, Mineral industry of Alaska in 1928: U.S. Geological Survey Bulletin 813, p. 1-72.

Reference (Deposit): Park, F.C., 1933, The Girdwood District, Alaska: U.S. Geological Survey Bulletin 849-G, p. 381-424.

Reference (Deposit): Jansons, Uldis, Hoekzema, R.B., Kurtak, J.M., and Fechner, S.A., 1984, Mineral occurrences in the Chugach National Forest, Southcentral Alaska: U.S. Bureau of Mines Open-File Report 5-84, 218 p., 2 sheets, scale 1:250,000.

Reference (Deposit): Smith, P.S., 1930, Mineral industry of Alaska in 1928: U.S. Geological Survey Bulletin 813-A, p. 1-72.

Reference (Deposit): Smith, P.S., 1942, Occurrences of molybdenum in Alaska: U.S. Geological Survey Bulletin 926-C, p. 161-210.

Reference (Deposit): Smith, P.S., 1933, Mineral industry of Alaska in 1931: U.S. Geological Survey Bulletin 844-A, p. 1-81.

Reference (Deposit): Smith, P.S., 1934, Mineral industry of Alaska in 1933: U.S. Geological Survey Bulletin 864-A, p. 1-94.

Reference (Deposit): Smith, P.S., 1939, Mineral industry of Alaska in 1937: U.S. Geological Survey Bulletin 910-A, p. 1-113.

Reference (Deposit): Capps, S.R., 1916, Gold mining in the Willow Creek district: U.S. Geological Survey Bulletin 642-G, p. 147-194, 195-200.

Reference (Deposit): MacKevett, E.M., Jr., and Holloway, C.D., 1977, Map showing metalliferous mineral deposits in the western part of southern Alaska: U.S. Geological Survey Open-File Report 77-169-F, 38 p., 1 sheet, scale 1:1,000,000.

Reference (Deposit): Cobb, E.H., 1979, Summary of references to mineral occurrences (other than mineral fuels and construction materials in the Anchorage quadrangle, Alaska: U.S. Geological Survey Open-File Report 79-1095, 184 p.

Reference (Deposit): Cobb, E.H., 1972, Metallic mineral resources map of the Anchorage quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-409, 1 sheet, scale 1:250,000.

Reference (Deposit): Martin G.C., Johnson, B.L., and Grant, U.S., 1915, Geology and mineral resources of Kenai Peninsula, Alaska: U.S. Geological Survey Bulletin 587, 243 p.

Reference (Deposit): Hoekzema, R.B., Fechner, S.A., and Kurtak, J.M., 1987, Evaluation of selected lode gold deposits in the Chugach National Forest, Alaska: U.S. Bureau of Mines Information Circular 9113, 62 p.

Reference (Deposit): Clark, S.H.B., and Yount, M.E., 1972, Reconnaissance geologic map and geochemical analyses of stream-sediment and rock samples of the Anchorage A-6 Quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map 351, 2 sheets, scale 1:63,360.

Reference (Deposit): MacKevett, E.M., Jr., and Holloway, C.D., 1977, Map showing metalliferous and selected non-metalliferous mineral deposits in the eastern part of southern Alaska: U.S. Geological Survey Open-File Report 77-169-A, 99 p., 1 sheet, scale 1:1,000,000.

Reference (Deposit): Berg, H.C., and Cobb, E.H., 1967, Metalliferous Lode Deposits of Alaska. U.S. Geological Survey Bulletin 1246, 254 p.

Reference (Deposit): Smith, P.S., 1939, Mineral industry of Alaska in 1938: U.S. Geological Survey Bulletin 917-A, p. 1-113.

Reference (Deposit): Smith, P.S. 1939, Mineral industry in Alaska in 1937: U.S. Geological Survey Bulletin 910-A, p. 1-113.

Reference (Deposit): Smith, P.S., 1938, Mineral industry of Alaska in 1936: U.S. Geological Survey Bulletin 897-A, p. 1-107.

Reference (Deposit): Smith, P.S., 1937, Mineral industry in Alaska in 1935: U.S. Geological Survey Bulletin 880-A, p. 1-95.

Reference (Deposit): Smith, P.S., 1936, Mineral industry in Alaska in 1934: U.S. Geological Survey Bulletin 868-A, p. 1-91.

Reference (Deposit): Brooks, A.H., 1922, The Alaska mining industry in 1920: U.S. Geological Survey Bulletin 722-A, p. 1-74.

Reference (Deposit): Smith, P.S., 1930, Mineral industry of Alaska in 1927: U.S. Geological Survey Bulletin 810-A, p. 1-64.

Reference (Deposit): Johnson, B.L., 1912, Gold deposits of the Seward-Sunrise region, Kenai Peninsula: U.S. Geological Survey Bulletin 520-F, p. 131-173.

Reference (Deposit): Smith, P.S., 1929, Mineral industry of Alaska in 1926: U.S. Geological Survey Bulletin 797, p. 1-50.

Reference (Deposit): Smith, P.S., 1941, Mineral industry of Alaska in 1939: U.S. Geological Survey Bulletin 926-A, p. 1-106.

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