- SMDI #
- 1206
- Current Showing Name
- Gunnar Mine
- Historical Showing Names
- Gunnar Mine, Gunnar Uranium Mine
- Company Name
- Government of Saskatchewan, Government of Canada
- Project Name
- UTM Easting (NAD83 Z13)
- 279532.3900
- UTM Northing (NAD83 Z13)
- 6589297.9400
- NTS Sheet
- 074N07
- TRM (Township-Range-Meridian)
- 120-17-3
- Primary Commodities
- Uranium
- Associated Commodities
- Copper, Iron, Lead
- Discovery Type
- Status
- Deposit: Post-Production
- Geological Details
- The Gunnar Uranium Mine open pit is located on the tip of Crackingstone Peninsula.
The mine area is underlain by N70°E/45°SE-trending, Aphebian age, well banded, fine-grained, uniformly brown paragneiss. The paragneiss consists of alternating, up to 1 foot (0.3 m) thick light (90% quartz-feldspar plus biotite, hornblende, and muscovite plus minor epidote, sphene, iron sulphides and andradite garnet) and up to 50 feet (15.2 m) thick dark (a similar rock which contains up to 30% biotite and hornblende) bands. The paragneiss, which is commonly veined with fine epidote stringers, is overlain conformably by the Gunnar Granite - a sequence of coarse-grained, pink- to orange-weathering, granitized microcline augen and porphyroblastic gneisses and metasomatic granite. The Gunnar Granite contains large elongate zones of alteration which are quartz-depleted, calcite-enriched and albitized. These tabular zones of alteration of low-quartz granitic rock have been named 'albite syenite' by the mine geologists. In places, the calcite has replaced quartz producing a 'calcite' syenite. Calcite has locally been leached out leaving a pitted vuggy rock called a 'sponge rock'.
The albitized granite host rock was subjected to severe brecciation. Three sets of non-orebearing faults converge in an area immediately southwest of the deposit. The St. Mary's Channel Fault is northwest-southeast/65° to 70°SW-trending normal right hand fault which has a displacement of up to 150 m (492.1 ft). The fault trace, which occurs on the paragneiss-syenite contact, consists of an up to 30 m (98.4 ft) wide zone of alteration, mud and breccia. The Fraser Fault is an east-west/45°S-trending, right hand normal fault with a displacement of up to 800 m (2624.7 ft). The Zeemel Fault is a west-trending strike fault which merges with the Fraser Fault at the orebody to form a broad zone of alteration and brecciation above the hanging wall of the deposit. A fourth older 40 to 55°SW-dipping fault, which predates both syenitization and ore emplacement, parallels the St. Mary's Channel Fault. There are two sets of jointing at the deposit. The first strikes north-south and dips subvertically and the second trends N70°E/50° to 60°SE. Movement along these joints is approximately 1 to 2 m (3.3 to 6.6 ft). Both albite alteration and ore emplacement appear to follow these joint systems.
The main orebody, which lies under 6 m to 20 m (19.7 to 65.6 ft) of muskeg and varved clays, consists of a subcircular pipe-like body within brecciated and albite-altered coarse-grained 'syenite' (formed by albitization of microcline-albite granite) adjacent to the contact with banded amphibole and sedimentary gneisses. This pipe is up to 137.1 m (450 ft) in diameter. The long axis of the pipe plunges 45°in a direction of 010° to 015° east for a length of 670.6 m (2,200 feet). At a depth of 300 m, the ore has thinned and virtually disappeared. Below 350 m, the ore pipe is lenticular and parallels the local strike.
Two smaller parallel satellite orebodies occur on the west flank of the main orebody. The larger of the two is 25 m (82.0 ft) in diameter and extends down-plunge for 180 m (590.6 ft).
The orebodies, which is located in brecciated portions of the syenite, consist of pitchblende, present as small (up to 5 cm (1.97 inch)wide) veins and patches, uranophane, and, near the surface, yellow secondary uranium minerals. Both sooty and lusterous varieties of pitchblende, the primary ore-forming mineral, are present as small veinlets, breccia infillings, cavity infillings, fracture plane coatings, and as disseminations throughout the host 'syenite'. Uranophane and beta-uranophane have a similar occurrence within the orebody. The secondary yellow uranium minerals occur as incrustations on pitchblende and as surface coatings on fractures near the surface of the orebody. Specular hematite, ilmenite, pyrite, chalcopyrite, and galena occur as scattered grains within chlorite or carbonate. Galena also occurs as minute stringers within the pitchblende. A single 4 cm wide vein of chalcocite was located.
- Geological Domain
- Beaverlodge
- Host Rocks
- Host Minerals
- Hematite, Ilmenite
- Indicators
- Exploration History
- 7/26/1989 In 1952, Albert Zeemel, while prospecting for Gunnar Mines, discovered radioactive boulders in a muskeg close to St. Mary's Channel. After staking and prospecting the site, 11 inclined drill holes, totalling 2,400 feet, were completed. The drill program outlined a widespread zone of pitchblende-bearing mineralization in the bedrock immediately beneath the muskeg.
The deposit was delineated with 179 vertical holes, totaling 70,000 feet, which were completed on a 75 foot square grid pattern (AF 74N07-0075). This work outlined an ore body about 450 feet in diameter, plunging from surface to a depth of 1,100 feet (335.3 m) below the shoreline of Lake Athabasca, and estimated to contain 4,000,000 tons of ore grading 0.2%.
Production commenced in September 1955 and from this date until 1958; ore was mined solely from an open pit. By the end of 1959 a shaft had been sunk 1,905 feet (580.6 m). From 1961 onwards the production came exclusively from the underground part of the operation. Underground mining continued until October 1963 when the ore body became depleted, and the mine closed in 1964.
In 1964 New Joburke Exploration Ltd. obtained a working permit on the Gunnar property to do more exploration. Further drilling was completed to search for additional possible ore.
- Production History
- Production Period: 1955-09-01 to 1964-12-31
5,500,000.00 tons
Production commenced in September 1955. Between 1955 and 1958, production came from an open pit. A 1905 ft (580.6 m) shaft was sunk in 1959 and production came from the open pit and underground until 1961. From 1961 to mine closure in 1964, production was exclusively from the underground operation. Ore was exhausted in October 1963 and the mine closed in 1964.
During the 8 years of operation, Gunnar mine processed about 5,500,000 tons of ore with an average grade of 0.175% U3O8.
GRADES OF ORE PRODUCED AT GUNNAR URANIUM MINE (PERCENT U3O8)
ORE UPPER LOWER MINE LEVELS
LOCATION 46 m 46 m 3 4 5 6 7 8 9 10
__________________________________________________________________________
open pit 0.173 0.175 ----- ----- ----- ----- ----- ----- ----- -----
underground ----- ----- 0.178 0.159 0.197 0.188 0.147 0.101 0.171 0.139
Summary:
- Uranium @ 0.18 %
- Reserves and/or Resources
- 1952-01-01
Albert Zeemel
4,000,000 tons ore grading 0.2%.
Summary:
Historic reserve (unspecified) of 4,000,000.00 ton
- Uranium: 4,000,000.00 ton @ 0.2 %