Hoidas Lake is a remote northern lake in the Canadian province of Saskatchewan.^[1] It is about 50 kilometres (31 mi) north of Uranium City. Named in honor of Irvin Frank Hoidas, a Royal Canadian Air Force pilot officer killed in action during the Second World War when his Stirling W-7520 crashed near the Belgian town of Sint-Truiden,^[2][3][4] it is the site of Canada's most advanced rare-earth element (REE) mining project.^[5]

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Hoidas Lake
Hoidas Lake Location in Saskatchewan Show map of Saskatchewan Hoidas Lake Hoidas Lake (Canada) Show map of Canada
Location	Northern Saskatchewan Administration District
Coordinates	59.928°N 107.820°W / 59.928; -107.820
Basin countries	Canada

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Hoidas Lake lies in the Northern Rae Geological Province, in the general vicinity of many of Saskatchewan's large uranium mines.^[5]

The mineralogy of the Hoidas Lake rare-earth deposit differs from most other such deposits in that it is hosted in veins of apatite and allanite.^[6] Hoidas Lake also differs from other deposits in that it contains a significant amount of heavy rare-earth elements, such as dysprosium.^[5] This abundance of heavy REEs is significant, as there is a growing demand for the heavier rare earths in high-tech manufacturing (such as the use of dysprosium in the manufacturing of hybrid car components).^[7][8] Mineralization is presumably hydrothermal, from an alkali or carbonatitic source at depth.^[9]

The main prospective zone is composed of two dominant rock types: a variably deformed monzogranite and a granodioritic to tonalitic gneiss. Both are Paleoproterozoic to Archean in age.^[10]

Ongoing work at Hoidas Lake has delineated a vein system (known as the JAK zone), which extends for at least a kilometer along the strike.^[9] The limits of the system have not been established along the strike nor along the dip,^[9] and the zone's total extension is therefore unknown. The resource zone averages 75 m in width^[11] and is composed of individual veins which, though ranging from one to eleven meters in thickness, average about three meters each.^[9] Veins are continuous to 300 m depth and follow an anastomosing (branching) geometry.^[9]

Estimates of the resource, given current delineations and assuming a 1.5% total rare-earth cutoff, have established a presence of at least 286,000 tonnes of rare-earth ore,^[12] which is enough to supply more than 10% of the North American market for the foreseeable future.

The Hoidas Lake claims are owned by Great Western Minerals Group, based in Saskatoon.^[5]

• List of lakes of Saskatchewan