The Arrow Deposit and other exploration targets at the Property belong to the unconformity-associated class of uranium deposits. This type of mineralization is spatially associated with unconformities that separate Paleo- to Mesoproterozoic conglomeratic sandstone basins and metamorphosed basement rocks (Jefferson et al., 2007).

The mineralization is known to occur at seven locations on the Rook I Property: 1) Arrow Deposit, 2) Harpoon occurrence, 3) Bow occurrence, 4) Cannon occurrence, 5) Camp East occurrence, 6) Area A occurrence, and 7) South Arrow occurrence, the most significant of which is the Arrow Deposit. All uranium mineralization discovered on the Property to date is hosted exclusively in basement lithologies below the unconformity.

ARROW DEPOSIT
Uranium was first discovered at Arrow by NexGen in February of 2014 when drill hole AR-14-01 intersected modest mineralization including 0.16% U3O8 over 9.0 m. Subsequent follow-up drilling identified a zone of extensive mineralization highlighted by drill holes AR-16-63c2, which intersected 15.20% U3O8 over 42.0 m and an additional 12.99% U3O8 over 46.5 m, AR-15-62, which intersected 6.35% U3O8 over 124.0 m, and AR-15-44b, which intersected 11.55% U3O8 over 56.5 m including 20.0 m at 20.68% U3O8 and 1.0 m at 70.0% U3O8. These drill holes intersected the mineralization at a low angle and therefore the core lengths do not represent the width of the mineralization.

Uranium mineralization at the Arrow Deposit dominantly occurs as uraninite. Other common uranium minerals include coffinite and secondary yellow coloured minerals, currently interpreted to be autunite, carnotite, and/or uranophane. A green coloured secondary uranium mineral interpreted to be torbernite has also been observed very locally. In zones of massive uraninite mineralization, blebs of a glassy black coloured phase with conchoidal fracture currently interpreted to be pyrobitumen are often observed.

Two key but contrasting types of uranium mineralization occur at Arrow:

• Open-space fillings
Open-space fillings include massive uraninite bodies interpreted to be uranium veins, and breccia bodies where the matrix is comprised nearly exclusively of massive uraninite. Uranium veins and breccias typically range in thickness from less than 0.1 m to greater than one metre and display sharp contacts with the surrounding wall rocks. Individual uranium veins usually occur at parallel to sub-parallel orientations to the regional foliation, however, at least one set of veins cross-cuts the regional foliation. Clasts present in uranium breccias at Arrow are typically fragments of the immediate wall rocks and often contain additional disseminated uraninite mineralization. Uranium breccias occur as both clast supported and matrix supported forms, with the latter typically hosting higher grades. Both styles of open-space filling mineralization are categorized by high uranium grades that can be in excess of 40% U3O8 and as high as 80% U3O8.

• Chemical replacement styles
Chemical replacement types of mineralization present at Arrow include disseminated, worm-rock and near complete to complete replacement styles. Disseminated mineralization is typically associated with strong to intense hydrothermal alteration where uraninite occurs as fine to medium grained anhedral crystals and crystal agglomerates spread throughout the host in concentrations of typically less than five modal percent. Worm-rock style mineralization is named for the wormy texture it by definition displays, which is the result of redox reactions between uranium bearing fluids and the host wall rocks. Typically, these redox fronts are less than 10 cm thick. Near to complete uraninite replacement of the host rock has also been observed at Arrow. These zones range in thickness from less than 0.1 m to greater than 1.0 m and, in contrast to open- space fillings, show gradual contacts. The presence of vugs in this style of mineralization and in some zones interpreted to be uraninite veins suggests that in at least some places, the veins may actually be the result of chemical replacement and not open-space filling. Uranium grades associated with chemical replacement styles of mineralization at Arrow range from less than 1% U3O8 in disseminated bodies to greater than 70% U3O8 in complete replacement bodies.

Hydrothermal alteration that occurs in the vicinity of Arrow is extensive and several distinct styles have been observed. In some areas, mineralization is closely associated with a pervasive quartz-sericite-sudoite-illite alteration assemblage that nearly completely replaces the host rock, although pre-alteration textures are often preserved. In other areas, mineralization is closely associated with pervasive brick red coloured hematite alteration. Another key alteration phase present at Arrow is dravite. Typically, it occurs in centimetre to decimetre wide breccia vein bodies beginning tens of metres from high grade uranium mineralization and increasing in size and frequency closer to mineralization. Carbon buttons are commonly observed in association with dravite. Centimetre sized drusy quartz veins occur ubiquitously in the vicinity of the deposit. Where proximal to high grade mineralization, these veins are often pink coloured.

The mineralization in the Arrow Deposit is sub-vertical and true width is estimated to be from 30% to 50% of reported core lengths based on currently available information.

Two longhole mining methods will be used to extract the ore:
- Transverse stope mining
- Longitudinal retreat stope mining.

Both longhole mining methods will use paste backfill to provide ground stability. This combination of longhole stoping using paste backfill will provide a combination of good productivity, high extraction, and stable back support.

All stope designs were completed using the Deswik Stope Optimizer (DSO) tool. The longhole stope design parameters were based on 30 m stope heights for both transverse and longitudinal stopes. For transverse stopes, the width of the primary and secondary stopes was set at 15 m, while a maximum strike length was not specified. For longitudinal stopes, the width of the stopes was set at a minimum of 3.0 m (including 1.0 m of dilution), and no maximum width, and a strike length of 15 m. After an initial result from DSO, a secondary evaluation of stopes with heights of 10 m and 20 m was completed to capture material that was not converted into mine shapes during the first pass.

Transverse longhole mining will be done using primary and secondary stoping methods. The order in which stopes are extracted is largely driven by the head grade, with the overarching goal of achieving annual production of 30.0 M lbs U3O8. Two separate vertical mining blocks (the Upper Block, and Lower Block) will be established, and within each vertical block, the A2 and A3 veins can be mined independently.

The Arrow deposit is planned to be accessed using two shafts. Both shafts will be located in the footwall of the deposit. They will both have an internal diameter of 6.5 m, and will be blind- bored concurrently, using conventional shaft sinking technologies.

The first shaft will be used as a production shaft, and for transportation of personnel and materials into the mine. Shaft #1 will be sunk to a depth of 658 m below surface. Shaft #1 will have divided compartments so that fresh air that comes into contact with ore being skipped to surface will be immediately exhausted within the mine. Shaft #1 will have a permanent headframe and hoisting house.

The second shaft will be used as an exhaust ventilation shaft. Shaft #2 will be sunk to a depth of 533 m below surface. An emergency escapeway system will also be installed in Shaft #2.

Ore Sorting and Storage
Ore will be crushed underground and will be suitably sized to feed the grinding mill. The hoisted ore will be loaded into an ore truck at the headframe. The truck will drive through a radiometric scanner to confirm ore grade and the delivery location of the ore on the ore pad. Different ore grades and types can be stored in different piles.

Grinding
A loader operator will deliver ore to the ore feed hopper. Traffic in the ore storage and reclaim area will be restricted to minimize ore contamination in the site area. A variable speed feeder belt will feed ore from the hopper into the semi-autogenous grind (SAG) mill at a prescribed rate that will be close to the ground ore feed rate to be fed to mill leaching. The ore will be weighed on the belt as well as given a gamma radiation scan to check uranium content.

Leaching
The first leach tank will be fed by a variable speed centrifugal pump to feed the prescribed solids rate to the leaching circuit. The leaching circuit will consist of six mechanically-agitated tanks that will be connected in series. The flow between each tank will be by gravity. The discharge of each tank will be from a baffled upcomer to ensure minimal solids short circuiting in each tank. The tanks in total will provide the target 10-hour residence time to oxidize and dissolve the uranium.

The tanks will be heated with steam spargers to the 50o C leach temperature. Most of the sulphuric acid required will be fed into the first two to three tanks. This will also be the case with the hydrogen peroxide oxidant that will be fed to the leaching tanks. Sulphuric acid will be added to maintain the target minimum 25 to 35 g/L acid content in the leaching tank discharge while the peroxide will be added to maintain the target >450 meV oxidation reduction potential (ORP).

It is expected that 99.3% of uranium in ore will dissolve in the leaching circuit.

Counter-Current Decantation
A variable speed pump will be used to pump slurry from leach tank 6 (the last tank of the leaching train) into a relatively small mix tank. Overflow solution from the countercurrent decant (CCD) 2 will report by gravity into this mix tank as well. The mixed slurry will be pumped to the center well feed of CCD 1 along with a flocculant flow. The overflow of CCD 1 (pregnant aqueous solution) will report to a pumpbox and will be pumped to feed a pin bed clarifier. Underflow from CCD 1 will be removed by a variable speed pump that will be controlled by the density of the underflow stream as well as the solids load level in the thickener. Underflow will be pumped to a small mix tank where it will be mixed with the gravity overflow of CCD 3. This mixed solution will be pumped to the feed well of CCD 2 where it will be treated with flocculant. In a similar manner, the CCD underflows will be pumped to feed the next CCD i.e. CCD 3 to feed CCD 4 until underflow of CCD 6 (the final CCD in the train). CCD 6 underflow will be pumped to the tails centrifuge feed tank in the paste backfill plant.

Pregnant Solution Clarification
The overflow from CCD 1 will feed a pin bed clarifier that will remove turbidity from the pregnant aqueous solution. The feed to the clarifier will be treated with a small quantity of flocculant to aid settling/clarification. The overflow of the clarifier will flow by gravity to the SX feed tank. The feed tank will have capacity to feed the SX circuit for about two hours. The small amount of underflow solids will be pumped back to feed the CCD 1 thickener.

Solvent Extraction
The organic in the SX circuit will be made up of three components:
- A tertiary amine that selectively forms a bond with uranyl sulphate. Enough amine will be added into the solution to hold the design g/L U3O8 (usually about 6–12% amine reagent by volume).
- Isodecanol that will be introduced into the solution to enhance the separation of aqueous and organic after mixing ceases. Isodecanol is typically added to about half the volumetric concentration of the amine.
- A kerosene-type organic as the main carrier solvent.

Gypsum Precipitation and Washing
Lime will be added to increase the pH of the loaded strip solution to remove the acid in the strip solution in preparation to precipitating uranium. Loaded strip solution will be pumped from the loaded strip tank into the first reactor tank of a train of seven tanks. The flow will report from one tank to the other by gravity. Lime slurry will be added to each tank to very gradually bring pH up in small steps to a final target value of 3.0. As lime is added, it will react with the strong acid solution to precipitate gypsum. Gradual addition into high agitation will ensure that precipitation happens as slowly as possible so as not to trap uranium in the gypsum particles as they are being precipitated. Precipitation will remove sulphate to the low levels that are required in the next uranium precipitation step. The total residence time in the gypsum precipitation circuit will be four hours.

Yellowcake Precipitation and Washing
Purified loaded strip from the gypsum clarifier overflow will report to yellowcake (YC) precipitation tank 1. In this tank, hydrogen peroxide will be added to precipitate uranyl sulphate as uranyl peroxide. The peroxide will be dispersed into a well-agitated slurry to minimize very fast localized precipitation. As the reaction progresses, the pH will begin to drop. A slurry of magnesia will be added to maintain the pH at 2.8 to 3.5. Tank 1 will flow by gravity to YC precipitation tank 2. In tank 2, the reaction will be completed and time will be given for the precipitate particles to grow. Total residence time in the YC precipitation tanks will be four hours.

Yellowcake Drying/Calcining and Packaging
Yellowcake from the YC centrifuge will be fed to the YC calciner by the YC conveyor. The calciner will be an indirectly-heated, rotary type. The calciner will be heated by natural gas. The combustion gas flow that heats the dryer drum will be kept uranium-free and will discharge through a stack. A small ventilating air stream will pass through the calciner to ensure that no gasses are concentrated in the calciner. Upon exiting, the gas will pass through a scrubber to remove any particulates. The liquid discharge of the scrubber will report to the YC wash tank 2. The gasses will discharge via a stack to the environment.

In the calciner, the damp uranyl peroxide will be dried, molecular water driven off, and uranium peroxide oxidized to produce a U3O8 product. The design temperature will be 840o C with a solids residence time of one hour. As well as oxidizing the yellowcake, a small amount of volatile contaminants will also be driven out of the calcine (e.g. fluorine).

The calcine bin will feed a packaging system that will load the calcine into 200 L steel drums. The drums will be sampled manually before lids are fitted and seal rings applied. The drums will then be washed thoroughly and dried. After being weighed, an ID label will be attached that includes the drum tare and total weight as well as the net weight of the product contained. The normal net weight of a drum will be about 400 kg. Typically, there will be about 100 drums packaged per mill operating day. Some empty drums will be stored in the packaging area. There will also be room in the packaging area for at least two days of production or about 200 drums. Lots will be loaded into truck vans and will be transported to the designated delivery point.