Canada

Star-Orion South (Fort a la Corne) Project

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Categories

Overview

Mine TypeOpen Pit
StatusCare and Maintenance
Commodities
  • Diamond
Mining Method
  • Truck & Shovel / Loader
Mine Life... Lock
SnapshotAt a meeting of the Fort à la Corne joint venture management committee held in June 2022, Rio Tinto Exploration Canada Inc. (RTEC) exercised its voting power to place the Project on care and maintenance through December 31, 2022.

RTEC advised Star Diamond that it intended to conduct a near-term review of its alternatives regarding the Project, including its potential exit.

Star Diamond continues to work with RTEC in assessing alternatives regarding the Project. These discussions remain at an early stage and there is no certainty that any agreement will be reached between Star Diamond and RTEC regarding any such potential arrangements.

Owners

SourceSource
CompanyInterestOwnership
Star Diamond Corp. 100 % Indirect
On March 26, 2024, Star Diamond Corporation announced the completion of its previously announced transaction with Rio Tinto Exploration Canada Inc. (“RTEC”) whereby RTEC has transferred to Star Diamond all of RTEC’s 75% interest in the Fort à la Corne diamond project.

Deposit type

  • Kimberlite

Summary:

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 of the Star Kimberlite have been emplaced contemporaneously with the deposition of the Mannville and lower Colorado sediments. However, the majority of the Star Kimberlite is interpreted to have erupted through the Mannville and into the early parts of the lower Colorado Group sediments (Joli Fou Formation time). The local lower Colorado and Mannville interface is situated approximately 170 m. The Mannville Group and Paleozoic interface lies approximately 340 m, as interpreted from the Company’s core drill holes.

The Star Kimberlite consists of two distinct types of kimberlite: dominant eruptive kimberlite and subordinate kimberlitic sediments. The eruptive kimberlite deposits at the Star Kimberlite are sub- divided into five main kimberlite phases emanating from a single vent, each with distinctive physical and chemical properties (Harvey et al., 2006 and Harvey, 2009a):
1. Cantuar Kimberlite;
2. Pense Kimberlite;
3. Early Joli Fou Kimberlite (“EJF”);
4. Mid Joli Fou Kimberlite (“MJF”);
5. Late Joli Fou Kimberlite (“LJF”).

All the major kimberlite phases of the Star Kimberlite have been proven to contain macrodiamonds.

Orion South Kimberlite Geology And Mineralization
Like the Star Kimberlite, the Orion South 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 97 to 121 m with an average of 105 m. Portions of the Orion South Kimberlite have been emplaced contemporaneously with the deposition of the Mannville and lower Colorado sediments. However, the majority of the Orion South Kimberlite is interpreted to have erupted through the Mannville and into the early parts of the lower Colorado Group sediments (Joli Fou Formation time). The local lower Colorado and Mannville interface is situated approximately 191 m below surface. The Mannville Group and Paleozoic interface lies approximately 347 m, as interpreted from drill holes. The Orion South Kimberlite is comprised of multiple eruptive units (or phases), each of which is texturally, mineralogically, physically and chemically distinct. Within the kimberlite, the units have cross-cutting relationships near conduits, but are stacked vertically within the volcanic edifice and crater / extra-crater deposits. Several conduits, feeding different units, have been identified on Orion South.

During Cantuar (Mannville Group) deposition, thought to be a time of continental fluvial-deltaic deposition (Zonneveld et al., 2004), kimberlite was deposited and reworked. Drilling indicates that the Cantuar-aged kimberlite deposits are generally thin (< 30 m thick) sheets occurring at multiple horizons within the Cantuar sediments. The bulk of the kimberlite deposits are confined within the marginal marine to marine sedimentary strata (Zonneveld et al., 2004) of the Upper Mannville Group (Pense Formation) and the lower Colorado Group (Joli Fou Formation). These kimberlite deposits are associated with the main crater excavation and crater fill. Proximal to the conduits and in close proximity to the base of the Mannville Group sandstone, the conduits flare (Scott-Smith et al., 1994) at a steep angle giving way to shallow angles near the margin of the craters.

The Orion South Kimberlite consists of two distinct types of kimberlite: dominant eruptive kimberlite and subordinate kimberlitic sediments. The eruptive kimberlite deposits at the Orion South Kimberlite are subdivided into six main kimberlite phases, each with distinctive physical and chemical properties (Harvey et al., 2009a & b):
6. Cantuar Kimberlite (“CPK”);
7. Early Pense (“P3”);
8. Pense Kimberlite (“Pense”);
9. Early Joli Fou Kimberlite (“EJF”);
10. Late Joli Fou Kimberlite (“LJF”);
11. Viking Pyroclastic Kimberlite (“VPK”).

Reserves

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Mining Methods

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Comminution

Crushers and Mills

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Processing

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Production

CommodityUnitsLOM
Diamond M carats 66
All production numbers are expressed as mineral.

Operational metrics

Metrics
Daily processing rate 45,000 t *
Annual processing capacity 14.3 Mt *
Waste tonnes, LOM 373 Mt *
Ore tonnes mined, LOM 528 Mt *
Total tonnes mined, LOM 901 Mt *
Tonnes processed, LOM 470 Mt *
* According to 2018 study.

Production Costs

CommodityUnitsAverage
Cash costs Diamond CAD 65 / carat *  
Assumed price Diamond CAD 370 / carat *  
* According to 2018 study / presentation.

Operating Costs

Currency2018
OP mining costs ($/t milled) CAD 4.37 *  
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* According to 2018 study.

Project Costs

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Heavy Mobile Equipment

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Personnel

Mine Management

Job TitleNameProfileRef. Date
....................... Subscription required ....................... Subscription required Subscription required Apr 16, 2018
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