Ontario Mineral Inventory

Ontario Geological Survey
Permanent Link to this Record: MDI52H09SE00008

Record: MDI52H09SE00008

General

Commodities

Primary Commodities: Gold

Location

Township or Area: Eva, Summers

Latitude: 49° 37' 5.03"    Longitude: -88° 2' 12.44"

UTM Zone: 16    Easting: 425110   Northing: 5496683    UTM Datum: NAD83

Resident Geologist District: Thunder Bay North

NTS Grid: 52H09NE, 52H09SE

Point Location Description: Map in Assessment report 52H09SE0012

Location Method: Data Compilation

Access Description: The Undersill property is located 7.5 km west-northwest of the town of Beardmore, straddling the Summers-Eva Township line. Travel northwest on Highway 580, which leaves Highway 11 110.5 km north of Beardmore, for 7.5 km. Turn south for 0.5 km on a narrow gravel road just before the Leitch Mine turnoff. Proceed be foot southwest from this point for approximately 1 km to the occurrence.

Exploration History

1910: Claims were staked by H. Murphy and P.J. McDevitt adjoining the Leitch property to the north. 1934: A second group of claims was staked by G. Maki, L. Farrow, and J. Farrow. 1936: Drilling, blasting, trenching and sampling was performed on several of the claims by H.G. Waring. 1944-1979: Various claims were staked, leased, cancelled, restaked etc. 1982-87: A group of 22 claims were staked by J. McMahon, M. Rentz, and W. Cox, including the old Murphy showings, south of the Leitch property. Geological mapping, trenching, and sampling was conducted over a flagged grid.

Assessment Work on File

Geology

Province: Superior

Subprovince: Wabigoon

Belt: Beardmore-Geraldton

Geological Age: Archean  

Geology Comments

Dec 07, 2005 (B Nelson) - The Undersill Occurrence lies at the western end of the main production belt, in the Beardmore-Geraldton camp. Gold mineralization, such as that found at the nearby Leitch Mine, is associated with the east-trending, coarse metasedimentary unit which includes comglomerate, wacke, argillite and magnetite-hematite-chert (+/- jasper) ironstone. Gold mineralization occurs in shear zones, quartz veins and breccia zones hosted in clastic metasediments, felsic intrusions, gabbros, sulphides within oside ironstone, and minor mafic metavolcanics. Isoclinal folding and tight drag-folding in the Beardmore area, specifically in the ironstone, appear to be necessary controls for ore structure development. Drag-folds and ore-bearing structures throughout the belt plunge westward at 25 degrees to 40 degrees. The country rock of the Murphy claims consists of greywack which strikes N70 degrees E and dips almost vertically to the north. A band of iron formation occurs on the property and has been traced by trenching and dip needle survey. Quartz veins have intruded into all the above formations. These veins pinch and swell laterally and vertically and vary in size from small stringers up to veins four feet wide. Many of the veins have a banded appearance due to chlorite forming in longitudinal cracks in the quartz.

Lithology

Lithology Comments

Dec 07, 2005 (B Nelson) - The greywacke is greenish-grey in color and has a clastic appearance. It has been sheared and altered to chlorite schist in many places. Where exposed in trenching, the iron formation in places shows alternate bands of jasper and magnetite while in other places it shows bands of slate with magnetite.

Mineralization

Mineralization Comments

Sep 30, 2019 (B Nelson) - Claim TB1355: The only important showing on this claim was a 12 inch vein marked 'No. 18' on an assay plan. This vein was drilled and blasted and a grab sample showed a value of 0.02 oz/ton Au. A channel sample taken 5 feet west of this showed 0.06 oz/ton Au over 5 inches. Claim TB1356: An 18 inch vein marked 'No. 17' on an assay plan yielded 0.02 oz/ton Au. A total of 32 grab samples was collected for gold analysis during the 1984 field season. All samples were taken from the main shear zone (greywacke, quartz vein and banded iron formation) and only 3 returned greater than trace amounts of gold. Sulphide mineralization occurs chiefly in the wall rocks at the contact with the veins but the minerals area also found to a lesser extent in the quartz. Arsenopyrite is also found and two specimens of galena were found in the quartz (Assessment report 52H09SE0012).

Alteration Comments

Dec 07, 2005 (B Nelson) - Crack seal textures with chlorite-sericite alteration predominate in the quartz vein material (alteration was also observed in sheared wall rock).

Mineral Record Details

Site Visit Information

Date: Jan 31, 1997

Geologist: B Nelson

Notes: The Beardmore-Geraldton Economic geologist visited the occurrence May 30, 1984.

References

File - Resident Geologist Mineral Deposit Files

Publication Number: Min Dep Date:

Author:

Publisher Name:

Location: Thunder Bay RGP

Map - Eva Township, District of Thunder Bay

Publication Number: P0601 Scale: 1:15,840    Date: 1997

Author: Mackasey W.O.

Publisher Name: Ontario Dept. of Mines

Location:

Mono - Gold occurrences, prospects, and deposits of the Beardmore-Geraldton area, districts of Thunder Bay and Cochrane

Publication Number: OFR5630 Page: 606-612  Date: 1986

Author: Mason J.K., White G.D.

Publisher Name: Ontario Geological Survey

Location:

Map - Summers Township, District of Thunder Bay

Publication Number: P0602 Scale: 1:15,840    Date: 1998

Author: Mackasey W.O.

Publisher Name: Ontario Dept. of Mines

Location:

Map - Tashota-Geraldton sheet, geological compilation series, Thunder Bay and Cochrane districts

Publication Number: M2102 Date: 1997

Author: Pye E.G., Harris F.R., Fenwick K.G., Baillie J.

Publisher Name: Ontario Dept. of Mines

Location:

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