Merinser

Prospect, Inactive

Commodities and mineralogy

Main commodities Au; Hg; Sb
Other commodities Cu
Ore minerals cinnabar; hematite; mercury; stibnite; unspecified copper and iron sulfide and oxide minerals
Gangue minerals calcite; quartz

Geographic location

Quadrangle map, 1:250,000-scale MM
Quadrangle map, 1:63,360-scale A-3
Latitude 63.1858
Longitude -151.2068
Nearby scientific data Find additional scientific data near this location
Location and accuracy
The Merinser prospect is on steep, north-trending ridge in the headwaters of an upper unnamed west fork of Slippery Creek. The prospect is in the NW1/4 sec.16, T. 20 S., R. 19 W., Fairbanks Meridian. A lode claim at the Merinser site (unnamed westernmost claim on fig. 4.1-B, Hawley and Associates, 1978) includes two deposits: a mercury deposit on the crest of the ridge; and a stibnite deposit on the southwest flank of the ridge. The coordinate location is at the mercury deposit site. It is accurate within 500 feet. The Merinser prospect is number 28 of Cobb (1972 [MF-366]; 1980, p. 69 [OFR 80-363]) and number 38 of MacKevett and Holloway (1977).
The Mt. McKinley A-3 quadrangle map shows an adit symbol at an elevation of 4300 feet. The adit is about 0.2 mile northeast of the mercury occurrence. It is possible that this adit is at a gold prospect tested in 1937.

Geologic setting

Geologic description

In structurally ascending order, the country rocks at the Merinser prospect consist of basic igneous flows, a limestone (marble?)-dark shale unit cut by thin granitic or felsitic dikes, and a granitic sill. The rocks strike NE and dip about 30 SE (Hawley and Associates, 1978, fig. 4.1-B). At least two types of mineral deposits occur on the property.
A deposit containing cinnabar, native mercury, iron and copper sulfides and their oxidation products occurs at an elevation of about 5000 feet on the ridge crest. The host rock was mapped as limestone by Earl Pilgrim (written communication, Oct. 16, 1929). As described by Moffit (1933, p. 321-322), dark-gray, altered sedimentary rocks are cut by light-gray granite or felsite. The occurrence was developed by a 36-foot-long open cut. Cinnabar and native mercury occur in a one-foot vein (W. E. Dunkle, Sept. 10, 1936 letter to J. G. Baragwanath). According to Dunkle, 'On top of one of the higher ridges what appears to be one of the veins carries no gold values but shows considerable cinnabar over a width of a foot or more and up to three or four percent of native quicksilver, which oozes out in drops and beads when this rock is broken.' The vein contains calcite and quartz. Iron and copper sulfides occur in small amounts, and iron oxide, including hematite, and oxidized copper minerals stain the rocks.
A nearly stratabound stibnite vein is exposed on the hillside southwest of the cinnabar deposit. It was developed by several pits. As mapped by Pilgrim, the vein could be followed for more than 500 feet; it dips about 30 SE. As described by Moffit (1933, p. 314), the stibnite is in a decomposed sandy bed highly colored by oxide minerals. The bed is capped by a thin, black shale unit and underlain by partly serpentinized dark igneous rock. Fragments of stibnite as much as 1 foot across were found below the vein zone and smaller fragments were dug from the vein.
A gold-bearing lode may occur at the location of the adit shown on the Mt. McKinley A-3 quadrangle. The topography of the area seems to match that described in a Sept. 9, 1936 letter from W. E. Dunkle to J. G. Baragwanath: 'We can start a drift tunnel on the vein at any one of several places but the handiest place will be in a very steep hillside with about 1000 feet over us to the top of the ridge.'
The mineralization is inferred to be Oligocene in age, related to the intrusion of the McGonagall pluton of Late Eocene or Early Oligocene age (Reed and Lanphere, 1973, 1974; Cole, 1998).
Geologic map unit (-151.209055885423, 63.1852775273416)
Mineral deposit model Multiple deposit types, including Almaden or silica-carbonate mercury deposits (27b or c), simple antimony deposit (27d), and possibly gold-bearing polymetallic veins (22b or c) (Cox and Singer, 1986).
Mineral deposit model number 27b or 27c, 27d, 22b or 22c
Age of mineralization The mineralization is inferred to be Oligocene in age, related to the intrusion of the McGonagall pluton of Late Eocene or Early Oligocene age (Reed and Lanphere, 1973 and 1974; Cole, 1998).
Alteration of deposit Oxidation of unspecified iron and copper minerals.

Production and reserves

Workings or exploration The cinnabar lode was developed by a 36-foot-long open cut; an associated stratabound stibnite lode was developed by small cuts. The prospect was discovered and developed before 1929 by W. J. Shannon, who also found the Straightaway Glacier (MM176) and Stibner (MM175) antimony deposits. The Merinser deposit(s) and possibly the other antimony deposits were actively prospected in 1930 (Smith, 1933). The Merinser deposit was visited by W. E. Dunkle in 1936 and probably was covered by the Greenback, Terminus, Magnet, and Old Sourdough claims optioned by Dunkle from Shannon in 1936 and 1937. An adit about 0.2 mile northeast of the mercury occurrence may have been the site of underground work on a gold lode in a granite dike (W. E. Dunkle, Sept. 10, 1936 letter to J. G. Baragwanath). The Shannon claims were abandoned by Dunkle at the end of 1937 or possibly early in 1938 (expense ledger, W. E. Dunkle, 1934-1937). The claims were subsequently restaked for antimony by Arley Taylor in the late 1960s and he attempted to develop the deposit. Chadwick (1976) thought that the attempt was premature, and that more exploration should be done before development.
Indication of production None
Production notes Possibly some mining of complex gold ore for metallurgical testing; possible hand-scale mining of stibnite.

Additional comments

The deposits are in Denali National Park and Preserve.

References

MRDS Number A011238

References

Chadwick, R. H. W., 1975, Gross mineral appraisal of Mt. McKinley National Park, Katmai National Monument, proposed Lake Clark National Park: Unpublished report, National Park Service, Alaska.
Cole, R. B., 1998, Early Tertiary post-subduction volcanism and deformation along the north side of the McKinley fault, Alaska [abs]: Geological Society of America. Abstracts with program, v. 30, p. 177.
Reed, B.L., and Lanphere, M.A., 1973, Alaska-Aleutian Range batholith--Geochronology, chemistry, and relation to circum-Pacific plutonism: Geological Society of America Bulletin, v. 84, no. 8, p. 2583-2610.
Reed, B.L., and Lanphere, M.A., 1974, Offset plutons and history of movement along the McKinley segment of the Denali fault system, Alaska: Geological Society of America Bulletin, v. 85, p. 1883-1892.
Reporters C.C. Hawley
Last report date 12/12/2000