|Quadrangle map, 1:250,000-scale||KC|
|Quadrangle map, 1:63,360-scale||B-6|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||The Easter prospect is at an elevation of about 150 feet in or near the valley of an unnamed, northeast-flowing creek that enters the west side of the north end of Tongass Narrows, about 0.5 mile south of Rock Point. The site is in section 36, T. 74 S., R. 89 E., of the Copper River Meridian. It corresponds to loc. 54 in Elliott and others (1978), and to loc. 265 in Maas and others (1995). The location is accurate within 0.1 mile.|
The country rocks on northern Gravina Island are chiefly Upper Jurassic to mid-Cretaceous andesitic and basaltic volcanic rocks that gradationally intertongue with flyschlike sedimentary rocks. The rocks are intruded by at least one pluglike body of Tertiary gabbro (Berg, 1973; Berg and others, 1988). The bedded rocks were regionally metamorphosed to low-greenschist grade in Late Cretaceous time, and subsequently contact metamorphosed to hornblende hornfels near the contact of the Tertiary gabbro. The country rocks are cut by a high-angle fault along Tongass Narrows that displays about 4 miles of right-lateral offset.The deposit is in slate and greenschist and consists of quartz fissure veins up to two feet thick that contain pyrite, a trace of arsenopyrite, and free gold (Brooks, 1902, p. 62-63). The principal vein was traced on the surface for 3800 feet. It strikes NW and dips steeply NE, at an angle to the foliation of the schist. Around 1901, the owners reported gold values of $3-$400/ton (Au at $20.67/oz.). At that time, the deposit had been explored by a six-foot-deep pit.
|Geologic map unit||(-131.810682892344, 55.4036456040657)|
|Mineral deposit model||Low-sulfide gold-quartz veins (Cox and Singer, 1986; model 36a)|
|Mineral deposit model number||36a|
|Age of mineralization||Late Cretaceous or younger.|
|Workings or exploration||Around 1901, the owners reported gold values of $3-$400/ton (Au at $20.67/oz.). At that time, the deposit had been explored by a six-foot-deep pit.|
|Indication of production||None|
Berg, H.C., Elliott, R.L., and Koch, R.D., 1988, Geologic map of the Ketchikan and Prince Rupert quadrangles, southeastern Alaska: U.S. Geological Survey Mineral Investigations Series Map I-1807, 27 p., scale 1:250,000.
Brooks, A.H., 1902, Preliminary report on the Ketchikan mining district, Alaska, with an introductory sketch of the geology of southeastern Alaska: U.S. Geological Survey Professional Paper 1, 120 p.
|Reporters||H.C. Berg, USGS|
|Last report date||7/1/1999|