Hyder Mica

Prospects, Inactive

Alternative names

Last Chance
Nakat Mica
Nakat Feldspar
Pegmatite Mica
Pearson
Mica City
Mrs. Mack

Commodities and mineralogy

Main commodities Mica
Other commodities Feldspar
Ore minerals muscovite
Gangue minerals quartz

Geographic location

Quadrangle map, 1:250,000-scale PR
Quadrangle map, 1:63,360-scale D-3
Latitude 54.776
Longitude -130.712
Nearby scientific data Find additional scientific data near this location
Location and accuracy
This site (Elliott and others, 1978, locs. 175-182) consists of eight occurrences in the Nakat Bay-Sitklan Passage area, all of which have been prospected for mica. Six of the prospects, known only from U.S. Bureau of Mines (1974) claim records, are named: Nakat Mica (Elliott and others, 1978, loc. 175; Sec 35, T. 81 S., R. 98 E., of the Copper River Meridian); Nakat Feldspar (loc. 176; Sec 35, T. 81 S., R. 98 E., of the Copper River Meridian); Pegmatite Mica (loc. 177; Sec 12, T. 82 S., R. 98 E., of the Copper River Meridian); Pearson (loc. 178; Sec 12, T. 82 S., R. 98 E., of the Copper River Meridian); Mica City (loc. 179; Sec 12, T. 82 S., R. 98 E., of the Copper River Meridian); and Mrs. Mack (loc. 181; Sec 18, T. 82 S., R. 99 E., of the Copper River Meridian). The two remaining prospects (Sainsbury, 1957, p. 156-159) are named Last Chance (Elliott and others, 1978, loc. 180; Sec 13, T. 82 S., R. 98 E., of the Copper River Meridian); and Hyder Mica (loc. 182; Sec 18, T. 82 S., R. 99 E., of the Copper River Meridian).
The coordinates are for the approximate center of the estimated four-square-mile area that encompasses this group of prospects; the coordinates of the center are accurate within about 0.2 mile.

Geologic setting

Geologic description

The Nakat Bay-Sitklan Passage area (Sainsbury, 1957, p. 152-161; Berg and others, 1988) is underlain by intensely folded and faulted Mesozoic or Paleozoic sedimentary, volcanic, and intrusive rocks that are regionally metamorphosed to greenschist and amphibolite grade. The metamorphic rocks locally are replaced or intruded by quartz-feldspar-mica pegmatite bodies that in places contain books of muscovite mica as much as eight inches in diameter (Sainsbury, 1957, p. 152-161; Cobb and Elliott, 1980, p. 142-143).
Massive pegmatite bodies at the Hyder Mica prospect (Sainsbury, 1957, p. 156-159) locally contain mica plates as much as 8 inches in diameter. The deposit was explored in the 1950s (?) by five trenches and several pits. Some of the mica was classified by state and federal agencies as 'strategic muscovite mica,' but most was of lower grade.
At the Last Chance prospect (Sainsbury, 1957, p. 156), a pegmatite body 2 to 3 feet thick contains thin books of silvery mica up to 1.5 inches in diameter. The estimated mica content of the pegmatite is less than 10 percent. The prospect was explored by a 4-foot-long trench.
Geologic map unit (-130.713655263587, 54.7756625467531)

Production and reserves

Workings or exploration The Hyder Mica prospect was explored, probably in the 1950s, by five trenches up to 40 feet long, and by several pits. Some of the mica was classified by federal and state agencies as 'strategic grade muscovite mica,' but most of the mica was of lower grade. The Last Chance prospect was explored by a four-foot trench.
Indication of production None

Additional comments

The site is in Wilderness of the Misty Fiords National Monument.

References