Unnamed (near Mathews Dome)

Occurrence, Inactive

Commodities and mineralogy

Main commodities Ag; Au; Cu
Ore minerals bornite; malachite; tetrahedrite
Gangue minerals calcite; quartz

Geographic location

Quadrangle map, 1:250,000-scale WI
Quadrangle map, 1:63,360-scale B-3
Latitude 67.4693
Longitude -151.4826
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence consists of rock samples collected by two government parties over a distance of about 2,000 feet immediately north of the summit of Mathews Dome. The occurrence is centered at an elevation of about 4,100 feet on the ridge about 0.2 mile north-northwest of the 4,618-foot peak of Mathews Dome, about 0.3 mile west of the center of section 36, T. 31 N., R. 17 W. The location is accurate.

Geologic setting

Geologic description

This occurrence consists of bornite, malachite, and possibly tetrahedrite in quartz veins in altered schist (Chipp, 1972). The rocks in the area consist of Devonian phyllite, schist, and subordinate limestone/dolomite (Chipp, 1972). Seven samples contained up to 0.1 part per million (ppm) gold, 14 ppm silver, and 2.1 percent copper. Kurtak and others (2002) reexamined the site and collected several samples. A 3-foot continuous chip sample of calcareous schist collected immediately north of Mathews Dome contained 8,630 ppm copper and a cross-cutting quartz vein at the same locality contained 4,003 ppm copper. Both the quartz veins and calcareous schist are overlain by green chlorite schist with sparse tetrahedrite, bornite(?), and malachite. The copper mineralization along the ridge is limited and discontinuous, extending for a quarter of a mile or less.
Geologic map unit (-151.485348902253, 67.4688487860616)
Mineral deposit model Unclear whether epigenetic, syngenetic, remobilized, or a combination of these.
Age of mineralization Devonian or younger based on the age of the host rock.
Alteration of deposit Oxidation of copper mineral(s). One sample of calc-schist is described as altered, but there is no description of the alteration.

Production and reserves

Workings or exploration Examination and sampling by the Alaska Division of Geological and Geophysical Surveys and the Bureau of Land Management. (Chipp, 1972; Kurtak and others, 2002).
Indication of production None
Reserve estimates None.
Production notes None.