Ontario Mineral Inventory

Ontario Geological Survey
Permanent Link to this Record: MDI52B13SW00004

Record: MDI52B13SW00004

General

Commodities

Primary Commodities: Gold

Secondary Commodities: Copper, Zinc, Silver, Lead

Location

Township or Area: Baker

Latitude: 48° 46' 53.7"    Longitude: -91° 45' 27.37"

UTM Zone: 15    Easting: 591267.85   Northing: 5403920.24    UTM Datum: NAD83

Resident Geologist District: Thunder Bay South

NTS Grid: 52B13SE, 52B13SW

Point Location Description: Shaft on a vein

Location Method: Conversion from MDI

Access Description: The Harold Lake Mine is located 10 km west-northwest of Atikokan. Access to the property is obtained by following the Valerie Falls Road for approximately 13 km from Highway 622 and then turning west on a secondary logging road and following it for approximately 6 km. The former Harold Lake Mine site can then be accessed by travelling southeast for 1.6 km along an all-terrain vehicle trail.

Exploration History

1894: Vein discovered. 1895-1896: 5 stamp mill constructed on the shoreline of Harold Lake 1896: 2 shafts, 2 adits, and an open stope on quartz veins. A 36 foot shaft with lateral development on the 26 foot level was sunk on the No. 1 vein (Lake shore vein). The No.2 Vein (McComber) has an open stope 75 feet long and 40 feet deep. Other quartz veins on the property have been stripped and trenched along with the development of 2 adits, one 59 feet long and the other 135 feet long. 1937: 17,000 square feet of stripping, trenching and sampling on several surface showings. Refurnished old workings by dewatering one shaft and putting new timbers in the old stopes. 1947: Stripping, blasting and trenching on various veins, no reported results. 1980: Detail mapping and sampling by S. J. Wilkinson from the Ontario Geological Survey. 1982: Camflo Mines Ltd. – magnetic and electromagnetic surveys.1987-88: Societe Miniere Mimiska Inc. conducted prospecting, geological mapping, geophysical surveys and diamond drilling (36 DDH totalling 13407 m). 1995-97: 888726 Ontario Ltd., A. Eveleigh, G. Clark, T. Maitland conducted prospecting, trenching, sampling, geophysical surveys. 2004: Canadian Empire Exploration drilled 4 DDH totalling 1164 m. 2011-12: Osisko Hammond Reef Gold Ltd. conducted prospecting, trenching, geological mapping, sampling, assays, and an aeromagnetic gradient survey.

Assessment Work on File

Geology

Province: Superior

Subprovince: Wabigoon

Belt: Calm-Lac des Mille Lacs

Geological Age: Archean  

Geology Comments

Mar 27, 2014 (Mark Puumala) - From OFR 6293 Mapping by Fumerton (1986) indicated that the Harold Lake Mine is located near the intersection between a west-southwest-striking lineament and a north-northwest-striking fault. Intense north- to north-northwest-striking shear-induced fabrics occur in the vicinity of the open stope and lakeshore shaft, with rocks in this zone altered to sericite, epidote, chlorite, albite, quartz and carbonate (Schnieders and Dutka 1985). This structural setting (i.e. intersecting faults) is similar to that described at the nearby Zephyr Zone, where gold mineralization has been interpreted to occur at the intersection between the east-northeast-striking Zephyr shear zone and the east-southeast-striking Ear Lake fault zone (Nelson 2005).

Lithology

Mineralization

Mineralization Comments

Mar 27, 2014 (Mark Puumala) - The mineralogy of the Harold Lake gold deposit is described by Schnieders and Dutka (1985) as follows. Moore (1940) reported that 18 veins are located on the original Harold Lake property. Narrow, discontinuous shear zones within the intrusive rocks host most of the veins. However, some veins are associated with the intrusion of felsic magma into mafic metavolcanics. Quartz is the principal vein component, with ankerite and pyrite. Secondary minerals in the veins include arsenopyrite, galena, sphalerite, chalcopyrite and gold. The quartz-carbonate veins which occur in the shear zones are commonly concentrated along the footwall of the shear zone at the interface between the schistose and relatively massive intrusive rock. Angular fragments of schist and granitoid rocks are frequently contained in the veins. Wilkinson (1982) reported shear zones of up to 10 metres in width with an average width of 2 metres. Those veins which are associated with granite intrusions, occur as numerous stringers and short, irregular bodies of quartz up to 2.4 metres (8 feet) wide. The Number l vein or "Lakeshore" vein is located on the west shore of Harold Lake and has an 11-metre shaft sunk on it, with lateral development on the 8-metre level. The vein strikes 330 degrees, dips 45 degrees southwest and has a continuous strike length of 50 metres. The width of the vein ranges from 30.5 to 75 centimetres. Mineralization consists of pyrite, galena, chalcopyrite, malachite, carbonate, sericite and gold. The Number 2 vein or “McComber” vein is located approximately 45 metres southwest of the Number 1 vein and strikes north with a dip of 55 degrees east. Developmental work on this vein includes an open stope 23 metres long and 12 metres deep. Where the vein is exposed on the bottom of the open stope it is only 36 centimetres wide and is barren of sulphides. Other development on the property consists of two adits and one 8-metre deep shaft to the west of the Number 2 vein. Various other quartz veins on the property have been stripped and trenched. Early exploration on the Harold Lake Mine property also included the driving of adits to follow two gold-mineralized vein systems that are located approximately 600 m west of the mine site. Larouche and Clark (1988) described the North and South Adit occurrences as follows. The North and South Adits have been driven into a tonalite face on either side of an east-west trending valley. Both adits follow quartz veins which assay over 1 oz/ton Au locally. The veins pinch and swell (10 – 100 cm) and are off-white in colour. The vein within the South Adit trends 320 degrees and dips 86 degrees north. A shaft is located 10 feet from the mouth. The total length of the vein/adit is 130 feet. The highest assays in this adit are associated with sulphide-rich sections of the vein (2.36 oz/ton Au). The quartz vein is hosted within a sericite schist contained in the tonalite intrusive. The vein within the North Adit trends 290 degrees and dips 82 degrees north. The vein is hosted by a sericite schist with numerous mafic dikes. The mafic dikes are chloritic and carbonate altered. The highest assay from the vein is 1.48 oz/ton Au. Both the North and South Adit veins are located within 50 metres of the tonalite-volcanic contact. Societé Minière Mimiska Inc. carried out an 8-hole diamond drilling program in 1987 to test for the down-dip extension of the North Adit vein system. All of these drill holes were successful in intersecting the host structure, which was logged as a 5.5 to 14 foot wide shear zone containing 1% to 20% quartz-carbonate veining mineralized with galena and disseminated pyrite. This mineralized zone is hosted by altered (sericite, saussurite and hematite) tonalite and mafic dikes. The most significant intersection (from diamond drill hole MH-87-13) returned 0.09 ounce Au per ton over 14.4 feet (Larouche and Clark 1988).

Mineral Record Details

Mineral Zones - Size and Shape

Site Visit Information

Date: Sep 27, 2013

Geologist: Mark Puumala

Notes: From OFR 6293 North Adit A large stripped outcrop area immediately adjacent to the historic North Adit exposes silicified and sericitized tonalite that is mineralized with disseminated pyrite. The rocks here are also cross-cut by numerous quartz stringers. Grab samples (MPHL1301 and 13DCKB004) of the altered tonalite collected from the southern end of the exposure contained anomalous gold values of 34 ppb Au and 251 ppb Au (Resident Geologist’s Files, Thunder Bay South District, Thunder Bay). Also near the southern end of the exposure, intense shearing and carbonatization envelops a wider quartz vein that appears to have been the main North Adit area exploration target. The shear zone/vein system at this location strikes 265° and dips 85° north. Further north in the stripped area, two approximately parallel, carbonatized mafic dikes cross-cut the tonalite. These dikes strike approximately 240°. The main mineralized quartz-carbonate vein at the North Adit occurrence is more clearly exposed to the west of the stripped area in an older exploration trench. The vein is approximately 50 cm wide and is mineralized with pyrite, chalcopyrite and galena. Sulphide mineralization within the vein is sporadic and occurs mainly near the tonalite contact. The vein strikes 265° and dips 70° north. A grab sample of sulphide-mineralized vein material (MPHL1302) returned 0.36 ounce Au per ton and 0.6 ounce Ag per ton (Resident Geologist’s Files, Thunder Bay South District, Thunder Bay). Harold Lake No. 2 (McComber) Vein Open Stope Area A large stripped area immediately adjacent to the No. 2 Vein open stope exposes an area of considerable lithologic and structural complexity. The northern portion of the trench is underlain by tonalite, while the southern end of the stripped area exposes a feldspar-porphyritic unit that either cross-cuts or grades into a bedded tuff. All of these lithologies are cross-cut by two lamprophyre dikes. One of these dikes strikes at 010° and bifurcates into two dikes near the southern end of the stripped area, while the second (apparently cross-cut by the other) bends into a shear that strikes 265° and dips 85° north. This shear also represents the contact between tonalite and the feldspar porphyry. Numerous quartz stringers, veinlets and veins occur in the tonalite south of the shear. The dominant trend of the quartz veins is approximately 310°. The tonalite also contains some disseminated sulphides. Molybdenite occurs in strongly silicified tonalite on the eastern side of the stripped area. A grab sample (MPHL1303) of quartz vein material mineralized with molybdenite and epidote was collected for assay and returned values of 178 ppb Au and 444 ppm Mo (Resident Geologist’s Files, Thunder Bay South District, Thunder Bay). South Adit A large expanse of outcrop (approximately 40 m long) has been stripped immediately south of the South Adit. The rocks exposed in this area appear to be a mixed sequence of mafic to felsic metavolcanic rocks cross-cut by a number of mafic dikes. The majority of the dikes tend to strike north; however, cross-cutting relationships can be quite complex. For example, one dike locally follows the foliation (striking 265°), possibly indicating syn-tectonic emplacement. A gold-mineralized quartz vein system is exposed immediately southeast of the South Adit. Many quartz veinlets and pods strike approximately parallel to the foliation (265°). However, the largest vein strikes approximately 320° and trends toward the adit opening. The quartz vein material contains pyrite, galena and chalcopyrite. A grab sample of this material (MPHL1304) returned 1.57 ounces Au per ton and 1.2 ounces Ag per ton (Resident Geologist’s Files, Thunder Bay South District, Thunder Bay).

References

MonoMap - Geology of the Righteye Lake area, District of Rainy River

Publication Number: R239 Date: 1986

Author: Fumerton S.L.

Publisher Name: Ontario Geological Survey

Location:

Map - Righteye Lake, Rainy River District

Publication Number: M2464 Scale: 1:31,680    Date: 1985

Author: Fumerton S.L., Kresz D.U.

Publisher Name: Ontario Geological Survey

Location:

Mono - Gold deposits of Ontario, part 1, districts of Algoma, Cochrane, Kenora, Rainy River, and Thunder Bay

Publication Number: MDC013 Page: 248  Date: 1971

Author: Ferguson S.A., Groen H.A., Haynes R.

Publisher Name: Ontario Dept. of Mines and Northern Affairs

Location:

Mono - Geology of the Righteye Lake area, District of Rainy River

Publication Number: OFR5299 Page: 56-62  Date: 1980

Author: Fumerton S.L.

Publisher Name: Ontario Geological Survey

Location:

Mono - Gold deposits of the Atikokan area

Publication Number: MDC024 Page: 44-46  Date: 1982

Author: Wilkinson S.

Publisher Name: Ontario Geological Survey

Location:

Mono - Property visits and reports of the Atikokan economic geologist, 1979-1983, Atikokan geological survey

Publication Number: OFR5539 Page: 248  Date: 1985

Author: Schnieders B.R., Dutka R.J.

Publisher Name: Ontario Geological Survey

Location:

Part - A tour of inspection in northwestern Ontario

Publication Number: ARV05.003 Page: 145-148  Date: 1998

Author: Blue A.

Publisher Name: Ontario Bureau of Mines

Location:

Part - Third report on the west Ontario gold region

Publication Number: ARV06.002 Page: 78-79  Date: 1998

Author: Coleman A.P.

Publisher Name: Ontario Bureau of Mines

Location:

Part - Geology and ore deposits of the Atikokan area

Publication Number: ARV48-02.001 Page: 28-31  Date: 1997

Author: Moore E.S.

Publisher Name: Ontario Dept. of Mines

Location:

MonoMap - Precambrian Geology of the Central Wabigoon Subprovince, Northwestern Ontario

Publication Number: OFR5422 Date: 2010

Author: Stone D.

Publisher Name: Ontario Geological Survey

Location:

Map - Precambrian Geology, Steep Rock Lake (West) Area

Publication Number: P3585 Scale: 1:10,000    Date: 2007

Author: Stone D., Lennox B.

Publisher Name: Ontario Geological Survey

Location:

Mono - Report of Activities 2013, Resident Geologist Program, Thunder Bay South Regional Resident Geologist Report: Thunder Bay South District

Publication Number: OFR6293 Date: 2014

Author: Puumala M.A., Campbell D.A., Tuomi R.D., Debicki R.L., Wilson A.C., Moses P., Brunelle M.R.

Publisher Name: Ontario Geological Survey

Location:

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For detailed information regarding this mineral record please contact the Thunder Bay South Resident Geologist District Office