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File Created: 09-Jul-1986 by Larry Jones (LDJ)
Last Edit:  03-Mar-1989 by Laura L. Duffett (LLD)

Summary Help Help

NMI
Name HIGHGRADE Mining Division Skeena
BCGS Map 103B062
Status Prospect NTS Map 103B12E
Latitude 052º 38' 04'' UTM 09 (NAD 83)
Longitude 131º 42' 26'' Northing 5835048
Easting 316804
Commodities Gold, Silver, Copper Deposit Types I01 : Au-quartz veins
Tectonic Belt Insular Terrane Wrangell
Capsule Geology

The property is underlain by massive and pillowed greenstones with minor interbeds of argillite, tuff and chert of the Vancouver Group, Upper Triassic Karmutsen Formation. The volcanics are cut by northwest trending faults with related ankerite-silica-sulfide mineralization up to 8 metres in width. A set of steeply dipping post-mineral faults, striking 020 to 060 degrees, are typically marked by low sulphide, chlorite alteration and bleaching, with thin up to 2 metre wide bull-quartz and calcite fillings. Visible sulphides consist of very fine acicular arsenopyrite and disseminated equant pyrite.

Gold mineralization occurs in several zones over a 1.5 kilometre northwest strike length. The mineralized zones are offset by northeast trending crossfaults. Better grades of mineralization occur in discontinuous pods, lenses and shoots of unknown orientation. Trenching and drilling indicated grades of mineralized zones ranged 1.7 to 10.6 grams per tonne gold over widths ranging from 0.5 to 8.0 metres. Silver values ranged 0.34 to 5.1 grams per tonne (Assessment Report 11834).

Showing #1 (original discovery) mineralization is developed in silicified or hornfelsed graphitic argillites interbedded within sheared pillowed greenstones. These sediments contain up to 10 per cent bedded syngenetic pyrite, but the higher gold values (0.34 to 1.37 grams per tonne gold) occur in zones of silicification with quartz veinlets and fracture pyrite. The mineralized zone is up to 10 metres wide and the best assay returned 1.37 grams per tonne gold over 1.5 metres.

Showing #2, 650 metres south-southeast of showing #1, is a 5 metre wide zone of variable mineralized and altered greenstones. A 2-metre wide core of silicified ankeritic clay-altered breccia contains 5 per cent disseminated pyrite and 5 per cent disseminated arsenopyrite. The best assay gave 11.6 grams per tonne gold over 1.0 metres.

Three hundred metres further south-southeast, showing #3 occurs over a 30-metre strike length in bleached greenstone fragment breccia. A 5-metre wide zone of strong silicification and ankerite alteration contains up to 3 per cent arsenopyrite and 3 per cent pyrite with minor chalcopyrite. A 6.0-metre sample returned 1.47 grams per tonne gold.

Two hundred metres southwest of showing #1 is Drill Site 83-04, which is part of a second parallel mineralized zone trending north- west, with several left lateral offsets. The best surface assay returned 5.35 grams per tonne gold over 1.5 metres and Drill hole 83-04 returned 13.58 grams per tonne gold and 5.1 grams per tonne silver over 0.26 metre. A drill hole 150 metres to the south gave 8.6 grams per tonne gold and 3.4 grams per tonne silver over 1.85 metres (Assessment Report 11834).

Bibliography
EMPR ASS RPT 9696, 10163, 10973, *11834
EMPR BULL 54
EMPR EXPL 1981-93, 221; 1982-354-355; 1983-492
GCNL *#218, 1982; #16,*#174, 1983; #165, 1986
IPDM May/Jun., 1983
GSC MAP 1385A
GSC P *88-1E, pp. 221-227; 89-1H; 92-1A, pp. 351-360

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