Occurrence, Inactive

Commodities and mineralogy

Main commodities Ag; Au; Cu
Ore minerals chalcopyrite; covellite; gold; malachite; pyrite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale SH
Quadrangle map, 1:63,360-scale B-1
Latitude 66.35
Longitude -156.24
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is at an elevation of about 3,000 feet on the Continental Divide in section 14, T. 11 N., R. 12 E., of the Kateel River Meridian. Cobb (1972, MF-448), locations 8, 9, 10 and Miller and Ferrians (1968), figure 3.

Geologic setting

Geologic description

The Dakli occurrence is at the northern edge of the Zane Hills pluton at the contact between Cretaceous hornblende-biotite granodiorite and Jurassic-Cretaceous andesite. According to Miller and ferrians (1968), copper and other minerals occur at three places along the contact . At locality 1, massive chalcopyrite in fractured quartz occurs in frost-riven blocks of meta-andesite. Pyrite, malachite, and covellite are also present. Grab samples of chalcopyrite in quartz contain as much as 150 ppm Ag, 0.8 ppm Au, 10,000 ppm Cu, 150 ppm Mo, and 1,000 ppm Zn. Several streams near this locality have meta-andesite float that is cut by sulfide-bearing quartz veins and contains disseminated sulfides. At locality 2, malachite and limonitic chalcopyrite occur in fractures in blocks of brecciated quartz, andesite and altered granodiorite in a zone 100 feet wide. Grab samples from this location contain as much as 30 ppm Ag, 0.09 ppm gold, 700 ppm Zn, 70 ppm Mo, and from 1,000 to 20,000 ppm Cu. At locality 3, a sample of sulfide-bearing quartz contained 1,000 ppm Cu, 2 ppm Ag, and 15 ppm Mo. At locality 4, about one mile south of the contact, rusty-colored molybdenite-bearing quartz veins as much as 2 feet thick cut the andesite near the granodiorite contact. A grab sample from one vein contained 2,000 ppm Mo. Sediments in streams draining the Dakli occurrence contain anomalous values of copper ranging from 100 to 300 ppm.
The intrusives and volcanics both show little or no hydrothermal alteration. Copper and traces of molybdenum minerals are essentially restricted to the contact between the granodiorite and andesite and to the quartz veins within the contact area (unpublished industry data, NANA Regional Corp. files).
Geologic map unit (-156.242663727179, 66.3494354508255)
Mineral deposit model Disseminated and massive sulfides in quartz veins cutting andesite and granodiorite.
Age of mineralization Cretaceous or younger.
Alteration of deposit Oxidation of pyrite and chalcopyrite to limonite and secondary copper minerals.

Production and reserves

Workings or exploration This occurrence was mapped by the U.S. Geological Survey in the mid 1960s (Miller and Ferrians, 1968). Numerous rock and stream sediment samples were collected and analyzed. A number of exploration companies examined the site during reconnaissance geologic programs in the 1970s and early 1980s.
Indication of production None