Royal Dutch

Occurrence, Inactive

Commodities and mineralogy

Main commodities Au
Ore minerals gold

Geographic location

Quadrangle map, 1:250,000-scale UN
Quadrangle map, 1:63,360-scale C-2
Latitude 53.88
Longitude -166.4228
Nearby scientific data Find additional scientific data near this location
Location and accuracy Near head of westernmost stream draining into Humpy Cove of Summer Bay, approximately 2.8 km inland.

Geologic setting

Geologic description

Randolph (1991) reports this occurrence is very similar to Misty Mountain (UN012). The prospect appears to be located within a transition zone between 2 regional rock packages. The lower package includes andesitic flows and tuffs and the upper package is a thick sequence of basaltic flows and lahars. Unlike Misty Mountain, both rock packages exhibit propylitic alteration, quartz veining, and intrusion by dioritic to gabbroic plutons (Randolph, 1991). A wide-spaced cockscomb quartz/arsenopyrite vein system covers an area approximately 600 by 1,000 feet (180 x 300 m) and the veins have a dominant trend of N 30 W. Veins approach 2 feet (0.7m) in thickness and vary in density from one vein to tens-of-feet to many veins per foot. In areas of high density veining the country rock is strongly propylitized and contains abundant epidote. Mineralization is restricted to the quartz veins.
Geologic map unit (-166.424697926139, 53.8791392877857)
Mineral deposit model Epithermal gold vein
Mineral deposit model number 25
Age of mineralization Late Tertiary or younger.
Alteration of deposit Regional propylitic alteration; increased (?) wall-rock propylitic alteration in association with veining.

Production and reserves

Workings or exploration Pan concentrate, rock, and soil sampling by BMEC (Randolph, 1991). Rock (vein) samples had gold values to 6.58 oz/t (225 ppm) gold, 0.1 oz/t (3.4 ppm) silver, and 6,167 ppm arsenic. Only two rock samples on NW margin of grid had anomalous mercury, but pan concentrates had high mercury. Twenty of 29 rock samples had gold greater than 130 ppb. Nineteen of those 20 contain more than 52 ppm As. Of the 8 rocks containing more than 400 ppm AS, 5 contained more than 1 ppm Au, suggesting a strong correlation between As and Au.
Indication of production None

References

MRDS Number A106007

References

Randolph, D.B., 1991, Unalaska project, 1990 final report: Battle Mountain Exploration Company, Alaska District, 62 p., 5 appendices, 15 plates, various scales. (Report held by the Aleut Corporation, Anchorage, Alaska.)
Reporters F.H. Wilson
Last report date 5/7/1996