The Strange Lake deposit is part of a post-tectonic, peralkaline granite complex which has intruded along the contact between older gneisses and monzonites of the Churchill Province of the Canadian Shield.

The granite complex is sub-circular and comprises a series of compositionally and petrographically distinct granites, which can be differentiated based on petrography (one feldspar versus two) and relative concentrations of the REE and HFSE, which generally exhibit unique ranges that are characteristic of each granite. These granites are in sharp contact with the surrounding country rocks and the apparent contact between the granite complex and country rocks is outward dipping at 20º to 30º. A structural zone comprising stockwork fluorite-hematite veining and hematite-fluorite breccia occurs discontinuously along the contact between the SLAC and country rocks. The least fractionated granite is a fine-grained, massive hypersolvus granite and it exhibits the lowest concentrations of REE and HFSE in the complex; it occurs in the geometric centre of the complex. This granite is surrounded by a medium-grained, massive subsolvus granite that exhibits a distinct enrichment in REE and HFSE. Within the subsolvus granite, pegmatite and aplite sheets and dikes occur, and these are the main host to REE and HFSE mineralization and represent the latest, most fractionated phase of magmatism in the complex.

Mineralization of interest at Strange Lake occurs within peralkaline granite-hosted pegmatites and aplites and, to a lesser degree, within the host granites, particularly in intrapegmatitic granites.

Pegmatites and minor aplite (fine-grained pegmatite) comprise gangue with feldspar (potassic>sodic), glassy to white quartz, arfvedsonite, gittinsite, fluorite and various minor accessory minerals including titanite, allanite, pyrochlore and gadolinite, which are readily identifiable in core. Gittinsite and amphibole appear to have generally formed contemporaneously and both exhibit euhedral to subhedral morphologies. Feldspar exhibits a variable paragenetic relationship relative to arfvedsonite and gittinsite, but is commonly somewhat later in complex pegmatites and earlier in simpler, late pegmatites. Quartz is late and interstitial and fluorite, which is commonly dark purple to black, is commonly later than quartz. Arfvedsonite is typically strongly replaced by either coarse bottle green aegirine or red-brown earthy hematite and may be strongly leached to form vugs that are sometimes quartz-hematite lined. Gittinsite is typically altered to a mottled orange-pink to beige colour and spotted with very fine grey-green LREE-bearing allanite, giving a spotted salt and pepper texture. Feldspar is often altered as concentric oscillating zones or mixed hematite and fluorite, giving a mottled, often fractured appearance.

Subsolvus granite, which typically contains very fine-grained dark grey to black rounded inclusions of hypersolvus granite is the most voluminous unit in the Strange Lake Alkali Complex (SLAC) and is the principal host to REE-bearing pegmatites. Minor white-grey mm-scale reaction rims locally wrap around these inclusions. It is typically fine- to mediumgrained (i.e., less than 1 cm) comprising variably altered feldspar (sodic>potassic), intergranular white-grey quartz, subhedral variably altered arfvedsonite, interstitial/poikilitic gittinsite and euhedral ghosts of narsarsukite; wispy pale purple or interstitial dark purple fluorite is ubiquitous. Extensive albitization of the granite creates an overall granular to sugary appearance in the groundmass while arfvedsonite, which commonly exhibits a bimodal grain size of fine mm-scale anhedral grains and relatively coarser-grained euhedral crystals, is variably altered or may be fresh. Similar to arfvedsonite in pegmatites, arfvedsonite is commonly altered either by aegirine, particularly proximal to pegmatites, or earthy brown-red hematite; large portions of the B Zone exhibit fresh arfvedsonite in a variably altered matrix. Narsarsukite, which is grey when unaltered, is often tan-beige, indicating replacement by titanite. Gittinsite is variable in colour, but is commonly partially replaced by dark grey-green LREE-bearing allanite; replacement may take the form of salt and pepper spotting as in pegmatites or as amorphous patches. Alteration typically developed in the host subsolvus granite is not typically developed in the inclusions.

A conventional open pit mining operation is proposed for the extraction of mineralized material from the B Zone rare earth element mineral deposit for the Strange Lake Project.

Mining will be undertaken by Quest using its own equipment and workforce. Specialized contractors will be used for the initial site clearing and initial haul road construction in preparation for the mining equipment fleet. Explosives, blasting agents, fuel and other consumables will be sourced from established suppliers.

The Strange Lake Project resources are contained in a single deposit. The open pit and internal phases were designed using Vulcan software, preliminary geotechnical designs, recommended standards for road widths and minimum mining widths based on efficient operation for the size of mining equipment chosen for the project.

The PEA flowsheet comprises crushing, grinding and flotation that will be undertaken as the Strange Lake site, followed by further processing at a facility at Bécancour. Processing at Bécancour will include acid thermal processing (acid bake) and water leaching to extract the payable elements into solution followed by hydrometallurgical precipitation to recover the rare earth elements and yttrium into a mixed REE+Y concentrate. The REE+Y concentrate will be treated to recover individual rare earth and yttrium oxides.

The crushing, grinding and flotation processing facility at Strange Lake is designed to operate for 365 days per year at a design throughput of 1,346,000 t/y for the first 23 years of the mine life. A plant expansion will enable the processing of up to 3,170,000 t/y of lower grade stockpiled mineralized material from year 24 onwards to the end of planned production.