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File Created: 24-Jul-1985 by BC Geological Survey (BCGS)
Last Edit:  28-Jan-2014 by Karl A. Flower (KAF)

Summary Help Help

NMI 092L3 Sia1
Name MICA, FAIR HARBOUR, MARK, LAURA LEE Mining Division Alberni
BCGS Map 092L005
Status Prospect NTS Map 092L03E
Latitude 050º 03' 29'' UTM 09 (NAD 83)
Longitude 127º 06' 18'' Northing 5546806
Easting 635641
Commodities Sericite, Mica, Silica Deposit Types
Tectonic Belt Insular Terrane Wrangell, Plutonic Rocks
Capsule Geology

The Mica occurrence is located on the south eastern shore of Fair Harbour.

The region is underlain by west striking, 040 to 060 degree south dipping rhyodacitic to basaltic-andesitic flows, tuffs and pyroclastics of the Lower Jurassic Bonanza Group. The volcanic rocks are intruded by granodiorites and related rocks of the Amai and Zeballos intrusions, located several kilometres to the south and east respectively. The intrusions are related to the Jurassic Island Plutonic Suite.

The occurrence is within an assemblage of chloritic andesite and fine to medium-grained tuff, intruded by a quartz-porphyry dike.

Mineralization occurs in an alteration zone along a fault striking west and consists of quartz and massive sericite with pyrite, magnetite and minor dumortierite.

In the visible exposures north of the base of the slope, the rocks have been highly altered, along the steep fault zone. The visible exposures indicated that the alteration is zoned but not enough can be seen to allow accurate measurements of zone widths. From the unaltered tuff northward, there is an intensely silicified band ranging up to 2 metres wide. Next is a band consisting of a mixture of fine-grained silica, sericite, and magnetite, and finally, an undetermined width of silicified and pyritized material.

Rock from the silicifed zone is pale, creamy white, often brown weathering, hard and fine-grained. A streaky foliation visible in some outcrops probably represents original bedding. In thin sections the rock is seen to consist of recrystallized quartz in grains with diameters of 0.01 to 0.12 millimetre, occasionally reaching 0.20 millimetre. Sericite and pyrite are present in minor quantities.

One channel sample cut along 3.4 metres in a shallow trench across the silica-sericite-magnetite zone contained: SiO2 = 64.52, Al2O3 = 22.11, K2O = 1.21, Na2O=0.22, Fe(total) = 4.50, H2O(+105 degrees C) = 4.20, SO3 = 1.54 (Geology, Exploration and Mining 1971, page 481).

In the early 1970‘s, Canadian Refractories Limited completed programs of geological mapping, geochemical sampling, surface stripping and trenching and three short drill holes. In 1980, the area was explored as the Mica property by J.T. Shearer.

Bibliography
EMPR ASS RPT *8931
EMPR GEM *1971-479,481
EMPR OF 1987-15
EMPR PF (Sharp, W.M. (1971-10-01): Preliminary Geological Examination - Fair Harbour Pyrophyllite Occurrence)
GSC ANN RPT 1886
GSC MAP 4-1974; 255A
GSC OF 9; 170; 463
GSC P 69-1A; 70-1A; 72-44; 74-8
GSC SUM RPT 1913; 1920A
Carson, D.J.T., (1968): Metallogenic Study of Vancouver Island with emphasis on the Relationship of Plutonic Rocks to Mineral Deposits, Ph.D. Thesis, Carleton University, Ottawa

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