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File Created: 24-Jul-85 by BC Geological Survey (BCGS)
Last Edit:  22-Jun-09 by George Owsiacki(GO)

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NMI 093A6 Sia1
Name HORSEFLY, FLY Mining Division Cariboo
BCGS Map 093A024
Status Developed Prospect NTS Map 093A06W
Latitude 52º 17' 24" N UTM 10 (NAD 83)
Longitude 121º 19' 32" W Northing 5794614
Easting 614203
Commodities Silica, Volcanic Ash Deposit Types R11 : Volcanic ash - pumice
Tectonic Belt Intermontane Terrane Overlap Assemblage, Quesnel
Capsule Geology

The centre of the Horsefly property is located approximately 9 kilometres southeast of the town of Horsefly. Access is via Horsefly and then Black Creek Road for approximately 9 kilometres. The west side of the property can be accessed by following Lowden Drive from Horsefly for 300 metres, 108 Mile Road for two kilometres, Wood Jam Road for 9 kilometres, then northeast on a rough road for two kilometres.

The region in which the showing is located forms part of the Quesnel Terrane. The Quesnel Terrane is an assemblage of Upper Triassic to Lower Jurassic sedimentary and volcanic rocks of the Nicola Group. The Nicola Group is overlain by alkaline basaltic volcanic rocks of the Miocene-Pliocene Chilcotin Group and calcalkaline volcanic rocks and sediments of the Eocene Kamloops Group. The Eocene sediments comprise mudstone, siltstone and shale.

The Horsefly deposit consists of poorly indurated volcanic ash which covers an area approximately 2.4 kilometres long by 300 to 400 metres wide. The ash has a more silicic composition than most of the Eocene volcanics in the region. The ash assayed 89.6 per cent silica, 0.21 per cent magnesium, trace sulphur and a moisture content of 0.55 per cent. Reserves are estimated at 27 million tonnes (Energy, Mines and Resources CORPFILE -Orofino Mines Ltd., 1960).

In 1960, Orofino Mines Limited conducted a preliminary investigation of the deposit. This investigation included a program of pit sinking, bulldozer trenching, and stripping. The deposit was classified as a lightly indurated pozzolanic ash. According to the American Society of Testing Materials, the deposit meets the chemical and physical requirements for N class pozzolanic material and can be used as a mineral admixture in concrete. The deposit was previously traced along the south side of the Horsefly River by outcrops, trenches and pits for a distance of approximately 2.4 kilometres and south and southwest from the river for 305 to 457 metres. The indicated tonnage of the deposit outlined by Orofino during the 1960 program was 30 million tons, however, the lateral extent of the deposit and its average thickness has never been investigated.

During a 2003 fieldwork program, limited exploration on the property could not verify the previous investigation by Orofino, however, several old bulldozer trenches were located. On the west side of the river where the Horsefly ash deposit is presumed to be located, rock exposure is very limited and several old bulldozer trenches were encountered. All trenches were filled with soil material and fresh, representative samples were almost impossible to collect. Sample Horsefly R1-2003 was collected from an old trench across an old road; the sample was not fresh enough to be representative for the volcanic ash of the old trench. Binocular microscope examination of the sample indicates the presence of unaltered volcanic ash with 60-70 per cent glass content and substantial amounts of soil. X-ray diffraction of the sample indicated 62 per cent glass content with substantial amounts of clay minerals (Assessment Report 27287).

Bibliography
EMPR FIELDWORK 1988, pp. 159-165
EMPR ASS RPT *27287
EMPR OF 1987-9; 1989-14, 20; 1990-31
EMPR BULL 97
EMPR P 1990-3
EMPR PF (In 093A General - Bergman, E.E., (1938): Report of a Geophysical Survey of the Horsefly River Valley, British Columbia; in Property File - Rimfire (Placer Development Ltd. (1984-03-15): Drill Hole Location Map - Horsefly)
EMR MP CORPFILE (Orofino Mines Limited, 1960)
EMR MR 181 p.A37
GSC MAP 12-1959; 1424A; 1538G
GSC OF 574; 844
CJES Vol.25, pp. 1608-1617

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