Ontario Mineral Inventory

Ontario Geological Survey
Permanent Link to this Record: MDI52A10NE00009

Record: MDI52A10NE00009

General

Commodities

Primary Commodities: Amethyst

Secondary Commodities: Barite, Lead

Location

Township or Area: McTavish

Latitude: 48° 41' 41.41"    Longitude: -88° 35' 1.18"

UTM Zone: 16    Easting: 383463   Northing: 5394743    UTM Datum: NAD83

Resident Geologist District: Thunder Bay South

NTS Grid: 52A10NE

Point Location Description: Lots 10 and 12, Conc. IV, McTavish Twp.

Location Method: Conversion from MDI

Access Description: Highway 11/17 east to the Superior Shores Road (formerly the Dorion Mine Road), just past Pearl, Ontario. Follow this road south for 4 km, cross the railway tracks and proceed straight (not the left) after the tracks. The parking lot and mine store are about 1 km from the tracks. Note: Before one gets to the parking lot and mine store, the road is gated, locked and posted No Trespassing as of May 6, 2016.

Exploration History

1975: Staked by Richard D. Middaugh, who in October of 1975 transferred all interests to James N. Barrett. 1976: April and May, manual and power-stripping performed by James N. Barrett. 1976: Autumn; AMRIC Amethyst Mine, a subsidiary of Rickaby Mines Ltd., purchased the property from J.N. Barrett. 1977: Purchased by Bill Miron from Rickaby Mines and changed the name (AMRIC Amethyst Mine) to Ontario Gem Company. 1982: Purchased by P. Marino. 2007: Mine closed.

Geology

Province: Superior

Subprovince: Wawa

Terrane: Wawa-Abitibi

Geological Age: Archean  

Geology Comments

Feb 25, 2020 (Andrew Tims) - The hanging wall is spotted red limey mudstone of the Sibley group; the footwall is porphyritic quartz-biotite monzonite. Ore minerals in the vein, in decreasing order of abundance are amethyst, barite and galena. The principle gangue mineral is white quartz. Numerous angular inclusions of Sibley mudstone are incorporated in the vein. The regional geology has been mapped by the Ontario Geological Survey (McIlwaine, 1971). This map shows the area to be underlain by Proterozoic Sibley Group mudstones and stromatolites resting uncomformably on Archean biotite-quartz monzonites. Lithological descriptions are as follows: “Well-layered beige mudstones predominate in the valleys of the area; variable bedding consistently dips away from the granitic knolls. The mudstones often grade up from basal sandy conglomerates. Stromatolitic units drape over the granites where the sandy conglomerate is not present. The granitic rocks have variable mineralogy and grain size. The most common composition is: a 5mm equigranular mosaic of 60% potassium feldspar, 20% quartz, 15% plagioclase feldspar, and 3-5% biotite. Factures in the granite are consistently at 084° and 355°.” Small quartz and amethyst veins parallel the regional fault at 025°. Large amethyst and quartz veins are often vug filled, and they are zoned with white quartz, pale lavender amethyst, dark purple amethyst and barite. Unique to this property is high quality stromatolitic amethyst.

Lithology

Lithology Comments

Jul 18, 2016 (Andrew Tims) - On the property, an amethyst bearing vein was noted in a fault zone at the contact (unconformity) between Sibley Group rocks and the Early Precambrian basement. The vein strikes N35°E and dips approximately 85°W. The vein is 1.8 to 2.4 metres (6 to 8 feet) wide and has an exposed strike length of approximately 46 metres (150 feet).

Mineralization

Mineralization Comments

Jul 18, 2016 (Greg Paju) - Barite occurs in a 10 to 15 cm (4 to 6 inch) wide zone along the hanging wall. The barite exhibits some well-developed bladed crystals. Some barite, occurring near the footwall exhibits rosette texture. The central portion of the vein consists of a breccia of silicified Sibley Group mudstone fragments cemented by white and amethystine quartz. The amethystine quartz ranges in colour from clear purple to dark purple to almost black. Crystal sizes exposed in the vein ranged from 5 to 10 mm. Large crystal clusters occur infrequently in some of the larger vugs. Several of the crystals are coated with a layer of hematite display a blood red to brown surface with a purple core. There are three pits exposed along the kilometre-long ridge. The first or main pit is kept fresh and cleared for tourists to pick amethyst. The second pit is quite small consisting of 1blast on the face of the ridge to expose the breccia. The third pit is located on a granite hill. A sliver of Sibley Group mudstones are exposed along one side of the hill. On top of the granite are patches of silicified stromatolites. Amethyst and cherty malachite occur between the stromatolite layers. A series of amethyst bearing veins, vugs and breccia zones are exposed along a strike length of 800 m. the dominant characteristic in pit A is the 040° fractures; whereas, the regional 025° fault is the most important genetic feature in pit C. Pit B is intermediate between A and C. A. The main quarry (6 X 100 m) is located on the northwest flank of a granitic knoll. A 3 m wide quartz breccia zone occurs to the south of the pit between granite and siltstone. Breccia fragments consist of both granitic and Sibley group rocks ranging in size from 0.2 to 20 cm with the majority of the fragments being less than 5 cm. fracture vein amethyst is accompanied by barite in the southern portions of pit A; as well, thin chloritic zones can be observed along fracture surfaces. Large bladed barite crystals coat fracture surfaces in the centre of the pit. Rare purple fluorite cubes (<0.5 cm) are also present. Small amethyst breccia zones occur in the northern portions of the pit. Sulfide mineralization (galena, sphalerite and pyrite) is present along the walls of the vein; galena is often disseminated as small (3 mm) crystals throughout the breccia zones. A large quartz, calcite, amethyst, galena vein occurs just north of the pit. The amethyst in this pit varies from pale purple to lavender in colour. B. A 1m wide quartz amethyst breccia zone is opened up in this pit. Granitic clasts are concentrated on the east side of the zone. The sediment/granite contact is not coincident with the 039° breccia zone in this pit. Fracture amethyst veins are orientated at 026°. C. High quality amethyst material occurs as crystals measuring 2 cm at base. These crystals line the large vugs in the central zone of this pit. This zone is augmented by an 024° breccia zone in the north portion of the pit. Galena rich quartz veins parallel the fractures in the granite. An 040° quartz, calcite, amethyst, galena, sphaleritic, and pyrite vein occurs to the south of the pit.

Mineral Record Details

Site Visit Information

Date: May 06, 2016

Geologist: Greg Paju

Notes: The site appears to be longer under operation. Access road is gated and significant logging has occurred up to the property’s northwestern boarder. The material within the main trench is a mixture of granitic rock, Sibley group and amethyst bearing material.

References

Compend - Annual report of the Regional and Resident Geologists, 1977

Publication Number: MP078 Scale:     Date: 1978

Author: Kustra C.R.

Publisher Name: Ontario Geological Survey

Location:

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

Publication Number: P0721 Scale: 1:15,840    Date: 1997

Author: McIlwaine W.H.

Publisher Name: Ontario Dept. of Mines and Northern Affairs

Location:

Compend - Annual report of the Regional and Resident Geologists, 1976

Publication Number: MP071 Scale:     Date: 1977

Author: Kustra C.R.

Publisher Name: Ontario Geological Survey

Location:

Mono - Industrial minerals of northern Ontario-supplement 1

Publication Number: OFR5388 Scale:     Date: 1982

Author: Vos M.A., Abolins T., Smith V.

Publisher Name: Ontario Geological Survey

Location:

Mono - Amethyst in the Thunder Bay Area

Publication Number: OFR5891 Scale:     Date: 1994

Author: Garland M.I.

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