Ontario Mineral Inventory

Ontario Geological Survey
Permanent Link to this Record: MDI31F02NW00035

Record: MDI31F02NW00035

General

Commodities

Primary Commodities: Uranium, Thorium

Secondary Commodities: Rare Earth Elements

Location

Township or Area: Miller

Latitude: 45° 7' 38.15"    Longitude: -76° 59' 19.49"

UTM Zone: 18    Easting: 343603.694   Northing: 4999011.862    UTM Datum: NAD83

Resident Geologist District: Southern Ontario

NTS Grid: 31F02NW

Point Location Description: Precise

Location Method: Conversion from MDI

Access Description: 10 km east-southeast of the town of Matawatchan. A gravel road heading north from Plevna reaches the east end of Long Schooner Lake. From here a boat is necessary to reach the occurrences on the north shore of Round Schooner Lake.

Exploration History

1954: Staking and sampling performed by T.F. Barnet and others.

Geology Comments

Jun 16, 2023 (Therese Pettigrew) - The area is underlain by highly metamorphosed (upper almandine amphibolite facies) sediments consisting of marbles, calc-silicate gneisses, plagioclase amphibolites with minor biotite, quartzplagioclase paragneiss and meta-arkose. These lithologies occur at the north and south ends of Round Schooner Lake. Running through the central portion of the lake is a thick section of granitic rocks, consisting of well-foliated granitic gneisses, migmatitic to layered biotite granitic gneiss, and late granites and granite pegmatites. This granitic sequence is very similar to the rocks of the "Faraday Granite" in the Bancroft Area, and is of approximately the same thickness. All of the above rocks form a unit dipping 20 to 40 degrees to the southeast (Masson and Gordon, 1981).

Lithology

Lithology Comments

Jun 16, 2023 (Therese Pettigrew) - Pink and white granite pegmatites, up to 20 meters long and 1 meter wide, intrude granite gneiss and biotite-hornblende gneiss (Gordon et al., 1981).

Mineralization

Mineralization Comments

Jun 16, 2023 (Therese Pettigrew) - Locally, uraninite, bastnaesite, zircon, and possibly allanite and uranothorite, are associated with magnetite, hematitization, and fracturing in the pegmatites (Gordon et al., 1981). : Occurrence "A": In an outcrop along shore about 325 m southwest of the outlet of the lake, pink granite gneiss intruding biotite-hornblende-quartz feldspar gneiss is intruded by a small pegmatite vein 20 m long and 1 m wide at the broadest point, pinching out at both ends. The pegmatite is mainly quartz and plagioclase (peristerite in part) with almost 5 percent magnetite ranging from a pinhead to 7.5 cm in grain size. The pegmatite averages 8 to 20 times background except where the pegmatite is fractured. Here it yields very high counts. Near the fracturing the pegmatite changes from a light pink to a yellowish red, due to the presence of hematite and limonite along the fractures. Magnetite occurs chiefly in quartz often surrounding crystals of zircon and bastnaesite. The zircon, which occurs mainly in quartz, is green, 0.5 to 1 mm long and with planar faces even when surrounded by radial fracturing. The radioactive minerals are uraninite, bastnaesite, zircon, and possibly allanite and uranothorite that occur as disseminated small grains in the three major minerals. A sample (R-77-87A-1) from the small, highly fractured, very radioactive portion assayed 490 ppm U308 and 390 ppm Th. Occurrence "B" is located 45 m east of the outlet of Round Schooner Lake. Biotite-hornblende-quartz-feldspar gneiss is cut by small bodies of magnetite-quartz-plagioclase pegmatite whose form ranges from even-walled lenticular dikes 15 to 90 cm wide to irregularly shaped masses 3-3.5 m across. Their radioactivity is mostly 2 to 4 times background except at sporadic concentrations of magnetite where radioactivity reaches 20 times background. The pegmatite also contains zircon and pyrite, giving it a spotty, rusty appearance. The sulfides were probably derived from the rusty-weathering pyritic calc-silicate and amphibolite country rocks. Peristerite, as in the "A" occurrence, is very common near areas of mineralization. The hottest radioactive areas were associated with fractured areas of the pegmatite. A selected sample (R-77-87B-2) of a highly radioactive portion high in magnetite gave an assay of 220 ppm U3O8 and 390 ppm Th. Occurrence "C" is located 225 m south of the southwest corner of Round Schooner Lake on lot 33, Concession XII; an outcrop 10 m by 35 m consists of two bands of pegmatite each with 3 m of exposed width separated by marble. The radioactivity is 1 to 2.5 times background except in an area 1 m2 that yields 5 times background (Masson and Gordon, 1981).

Mineral Record Details

References

Map - Geological series, radioactive mineral deposits of the Pembroke-Renfrew area, southern Ontario

Publication Number: P2210 Scale: 1:126,720    Date: 1980

Author: Masson S.L., Gordon J.B., Storey C.C.

Publisher Name: Ontario Geological Survey

Location:

MonoMap - Radioactive mineral deposits of the Pembroke-Renfrew area

Publication Number: MDC023 Page: 94-97  Date: 1981

Author: Masson S.L., Gordon J.B.

Publisher Name: Ontario Geological Survey

Location:

Mono - Uranium and thorium deposits of southern Ontario

Publication Number: OFR5311 Page: 32  Date: 1981

Author: Gordon J.B., Rybak U.C., Robertson J.A.

Publisher Name: Ontario Geological Survey

Location:

Report an Error

We are continuously updating our assessment file / technical report information. If you notice errors in the data, please contact us.

Terms of Use

Please review our Terms of Use agreement for this data product.

Ministry Contact Information

For detailed information regarding this mineral record please contact the Southern Ontario Resident Geologist District Office