Ontario Mineral Inventory

Ontario Geological Survey
Permanent Link to this Record: MDI000000002028

Record: MDI000000002028

General

Commodities

Primary Commodities: Amethyst

Location

Township or Area: McTavish

Latitude: 48° 41' 26.44"    Longitude: -88° 41' 48.6"

UTM Zone: 16    Easting: 375125   Northing: 5394460    UTM Datum: NAD83

Resident Geologist District: Thunder Bay South

NTS Grid: 52A10NE

Point Location Description: Visible on Google Earth

Location Method: Field Visit with GPS

Access Description: Turn left onto Road #5 North in the community of Pearl, cross the railway tracks, and then proceed left for 1.9 km kilometres turning left again traveling northwesterly along a 4x4 gravel road for 3 km to the access to the quarry on the right. You have travelled to far north if you encounter a hydro tranmission corridor.

Exploration History

1967: staked by G. Noyes, who carried out stripping and trenching. 1970: G. Noyes carried out stripping and trenching. 1977: claims brought to lease. 2015: Operated under the authority of MNR Aggregate Permit No.625989, which allows for the extraction of up to 500 t/year from a quarry area of 58 ha. 2012: M. Noyes carried out prospecting. 2015-17: Mitchell and Martin Noyes carried out prospecting, stripping, and trenching.

Assessment Work on File

Geology

Province: Superior

Subprovince: Quetico

Geological Age: Archean  

Lithology

Mineralization

Mineralization Comments

Feb 25, 2020 (Therese Pettigrew) - The property is located on the east half of Concession V and north half of Lot 4, McTavish Township. The first occurrence is in the bed of a creek near a set of falls (4.5 m high) and was described by Kustra (1969): “this amethyst occurrence occupies a vertically dipping fault zone, striking N70E, at the contact between red Archean granitic rock and dolomite and argillite of the Sibley Formation. A trench, 18 m long, 2 m to 3 m wide and 2 m deep exposes a network of white quartz and amethyst veins, approximately 2 m wide. Locally the amethyst veins attain a width of 1 m and where the material forms vugs, crystals up to 7 cm in diameter occur. Angular fragments of dolomite and granite are enclosed by vein matter. A very minor amount of pyrite, chalcopyrite and galena also occurs. Adjacent to the fault, the granite is altered and epidotized and has a radioactive count of not more than 1.5 times background.” The breccia zone contains 20-30% quartz, 70-80% angular granitic clasts up to 3 cm in size, 5-10% vugs commonly filled with clay. Amethyst is pale lavender to black. The West Pit occurrence (location of this MDI) is 300 m west of the Falls occurrence and occurs in the side of a 9 m hill. The trench is 25 m x 4.5 m x 2.4 m. Two vein breccia zones 80/80 degrees and 50/90 degrees are exposed. The 80/90 zone cuts the 50/90 zone. Both are 1 m to 2 m wide, hosted in a quartz monzonite (red, medium-grained, 10-20% quartz, 85% red feldspar, minor amphibole). The zone contains 35-60% angular fragments of monzonite, 30-40% white quartz and 10-15% vugs; most are lined with 1 cm or less white, smokey to light purple amethyst. Where the two zones intersect, two large vugs 0.6 x 1 x 2 m and 1 x 1 x 1 m occur. The vugs are partially clay-filled and lined with 8 cm crystals, some are hematite coated. The Hydroline Occurrence is reached by following the bush road 30 m west where the road branches (north and south), take the southern branch for 425 m to the powerline. The occurrence is on the north side of the outcrop on a 6 m cliff face. A series of quartz veins 8 cm to 40 cm wide across a zone 40 m wide. The zone strikes 119/90 degrees. Sections contain vugs from 30 to 60 cm across, clay-filled lined with dark purple amethyst up to 30 cm across, often hematite coated. The host rock is quartz monzonite (Thunder Bay mineral deposit files).

Mineral Record Details

References

Map - Geological series, McTavish Township (west part of north half), District of Thunder Bay

Publication Number: P0720 Scale: 1:15,840    Date: 1997

Author: McIlwaine W.H.

Publisher Name: Ontario Dept. of Mines and Northern Affairs

Location:

Mono - Amethyst deposits of Ontario

Publication Number: GB05 Scale:     Date: 1998

Author: Vos M.A.

Publisher Name: Ontario Division of Mines

Location:

Article - Port Arthur District

Publication Number: MP023.003 Scale:     Date: 1997

Author: Kustra C.R.

Publisher Name: Ontario Dept. of Mines

Location:

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Ministry Contact Information

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