The Crater Lake Deposit is a large, scandium- and REE-bearing alkali igneous intrusive complex. Carbonatite and alkaline intrusive complexes (as well as their weathering products) are the primary sources of REE. Apart from REE, these rock types can also host deposits of niobium, phosphate, titanium, vermiculite, barite, fluorite, copper, calcite, and zirconium. Although these types of deposits are found throughout the world, only six are currently being mined for REE: five carbonatites (Bayan Obo, Daluxiang, Maoniuping, and Weishan deposits in China, and the Mountain Pass deposit in the USA) and one peralkaline intrusion-related deposit.

The Crater Lake syenites are interpreted to be a late differentiate product of the Mistastin Batholith. The dominant exposed lithology is coarse- to medium-grained, massive syenite, which is mainly composed of perthitic K-feldspar and 1 to 10% by volume of interstitial ferromagnesian minerals (Petrella 2012). A magnetic and melanocratic unit, ferro-syenite, which commonly contains greater than 50% by volume of ferromagnesian minerals, occurs as large continuous to discontinuous subvertical and conical bodies, sills, narrow dikes and inclusions in the felsic syenites. Three large ferro-syenite bodies have been found on the property: TGZ, Boulder Lake and STG. Petrella (2012) interpreted the narrow ferro-syenite dikes as having formed by fractional crystallization of ferromagnesian minerals, leaving behind a residual magma that produ ........

The mining method selected for the Crater Lake project is a conventional drill and blast mine operation with truck and shovel excavation and transport of blasted material.

Mine production to feed the processing plant will begin in Project Year 1 and will average 426,100 t of mineralized material per year until Year 24 and decrease to 351,539 t at year 25. The life of the mine is 25 years. Mineralized materials will come from the Starter Pit in Year 1 and Year 2, then from the Middle Pit from Year 2 to Year 9, and finally from the Ultimate Pit from Year 9 to Year 25.

It was assumed in this PEA that overburden removal and hard rock mining will be performed by the Owner. Other scenarios involving contractors were not contemplated for this study, but such scenarios should be investigated during future studies on this project.

The overburden material is mainly constituted of glacial till at variable thicknesses, ranging from 0 m to approximately 10 m in the pit area. No drill and blast activities are planned for the removal of overburden removal.

The ore and waste rock material will be drilled and blasted in 10 m benches, then loaded into rigid-frame haul trucks with hydraulic shovels and wheel loaders.

In-pit haul roads and ramps are designed with an overall width of 22.5 m on overburden and rock. All ramps and haul roads are designed for double-lane traffic, except for the last two benches in the pit bottom which are design ........

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