Moonlight Divide

Prospect, Inactive

Commodities and mineralogy

Main commodities Cu
Ore minerals malachite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale SO
Quadrangle map, 1:63,360-scale D-5
Latitude 64.795
Longitude -164.448
Nearby scientific data Find additional scientific data near this location
Location and accuracy The Moonlight Divide prospect is located on the ridge crest betweeen the headwaters of Moonlight Creek (SO099) and Ridgeway Creek (SO092) at about 1,400 feet elevation. This is locality 14 of Cobb (1972, MF 445; 1978, OF 78-181). Gamble (1988) shows two occurrences of this name farther west and this as his new locality 125.

Geologic setting

Geologic description

This prospect is one of many occurrences of copper mineralization in silica-rich rocks near the regional contact between marble in a lower Paleozoic metasedimentary assemblage and pelitic schist of possible Cambrian or Precambrian age (Till and others, 1986). This type of copper occurrence is present at several localities in the western Solomon quadrangle and has similarities to several in the Kougarok area of the northeastern Teller quadrangle. In the Teller quadrangle, the Ward mine (TE071) is an example of this type of copper mineral occurrence. The Ward mine has been described as a zone of silicification in marble above a thrust contact with underlying metapelitic schist (Sainsbury and others, 1969; Sainsbury, 1975, p. 90-94). The silica-rich rocks have been metamorphosed and commonly have a laminar fabric. Copper-bearing minerals, mostly malachite but also including azurite and in places chalcopyrite and possibly bornite, are disseminated in the silica-rich rocks. The minor sulfides tend to be along faint laminae and joints (Sainsbury and others, 1969, p. 22). Malachite and azurite also occur in small veins and veinlets in the silica-rich rocks. The summary characterization of this type of Seward Peninsula mineral deposit by Sainsbury (1975, p. 90-94) contains inconsistencies with some descriptions of these deposits. Their origin is uncertain and other possibilities should be considered. One possiblity is that the silica-rich rocks are quartzites and that there is a stratigraphic control to the Ward deposit and similar occurrences elsewhere on Seward Peininsula. Quartzite at the base of the regional carbonate assemblage is recognized elsewhere in the Kougarok Mountain area (Puchner, 1986, p. 1777). Gamble (1988) describes rocks near this prospect as an iron-stained quartzite (or silicified marble) within marble with 2 to 3 percent pyrite; a sample contained 400 ppm As.
Geologic map unit (-164.450618491231, 64.7942568044662)
Mineral deposit model Copper-bearing mineralization in silica-rich zones at base of marble overlying metapelitic schist.
Age of mineralization Unknown; if stratigraphic controls are important then it is probably Paleozoic in age.
Alteration of deposit Silicification? The development of silica-rich rocks at or near the the base of Paleozoic marble overlying metapelitic rocks characterizes this type of copper occurrence.

Production and reserves

Workings or exploration Some shallow prospect pits were dug and claims were staked (Smith, 1908).
Indication of production None


MRDS Number 10308278


Puchner, C.C., 1987, Geology, alteration, and mineralization of the Kougarok Sn deposit, Seward Peninsula, Alaska; Discussion reply: Economic Geology, v. 82, p. 2201-2204.
Reporters Travis L. Hudson (Applied Geology)
Last report date 8/19/1999