Fort À La Corne Kimberlite Model
Unlike the idealized South African kimberlite model (Hawthorne, 1975), the majority of the FalC kimberlites are mainly shallow bowl-shaped kimberlites which have kimberlite footprints ranging up to 2,000 m wide and extending to depths ranging from approximately 100 m to greater than 700 m.

The limited deep drilling, however, precludes any interpretation of the shape of the kimberlites below about 450 m. Therefore, at depth, the FalC kimberlites may, in fact, resemble the idealized South African model.

FalC kimberlites were emplaced into poorly consolidated Cretaceous-aged clastic and marine sedimentary rocks. They are generally interpreted to be in the form of stacked, sub-horizontal lenses or shallow zones of crater facies material with associated pyroclastic flow and fall deposits of large lateral extent. The kimberlite phases are classified entirely as crater-facies pyroclastic kimberlite, although a number of kimberlite units may be distinguished according to their grain size, style of emplacement, primary and chemical alteration and the abundance and presence of olivine macrocrysts.

Star Kimberlite Geology And Mineralization
The Star Kimberlite was deposited within the Cretaceous sedimentary rocks of the lower Colorado and Mannville groups, which unconformably overlie Paleozoic limestones and dolomites. The glacial overburden thickness ranges from 90 to 130 m with an average of 92 m. Portions o ........

Mining is carried out using conventional open pit mining. The Orion South kimberlite is mined first, followed by the Star kimberlite.

Pre-Stripping
There is a considerable amount of unconsolidated overburden that is removed during a four-year pre-stripping period. The vast majority of this overburden is removed using three bucket-wheel excavators (“BWEs”).

Merchantable timber is harvested prior to stripping. A fleet of excavators and articulated trucks excavates a 20-30-metre-deep starting “key” or “slot” for a BWE. After that BWE has progressed for a period, enough space will be cleared behind it to allow a second, deeper key to be excavated – again using the excavator and articulated truck fleet. Then, the second BWE starts operating. The same procedure is used to establish the third BWE.

BWE spoil is removed from the pit on overland conveyors and delivered to a single, large spreader. This crawler-mounted spreader places the spoil on the waste pile.

Kimberlite Mining
Hydraulic shovels load the kimberlite into rigid-frame trucks. It is estimated that seventy percent of the kimberlite will require drilling and light blasting. The powder factor will be quite low to avoid diamond breakage.

The trucks transport the kimberlite to an in-pit mineral sizer, which crushes larger lumps before placing the kimberlite onto an overland conveyor for transport to the mill stockpile.

Backfilling
The Or ........

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