Name of the Project
Cape Flattery silica sand project.

Location
Eastern coastline of Cape York Peninsula in North Queensland, Australia.

Project Owner/s
Diatreme Resources. The project was acquired in 2024 and is currently held within the Diatreme group. Diatreme announced on April 13, 2026, that its wholly owned subsidiary, Metallica Minerals, had agreed to sell Cape Flattery Silica to Cape Silica Holdings, the joint venture (JV) between Diatreme and Sibelco Silica, subject to shareholder approval and other conditions precedent.

Project Description
An updated definitive feasibility study (DFS) is under review, with Diatreme assessing potential synergies between Cape Flattery and its flagship Northern Silica Project to facilitate shared infrastructure and reduced capital expenditure. 

The project has an estimated ore reserve of 47-million tonnes and a total JORC mineral resource of 61-million tonnes. 

The updated DFS proposes the extraction and processing of raw sand to produce a high-purity silica sand product for glassmaking, including solar PV glass, for export through Cape Flattery. 

The project will comprise a conventional resource extraction and off-the-shelf processing plant with an operating capacity of 1.8-million tonnes a year. 

A purpose-built jetty is planned, subject to development approval, to allow for barge loading and transshipping operations. 

The project includes the overland conveyor from the product stockpile to the jetty infrastructure facility, the barge loading facility and associated jetty, a purpose-built accommodation facility, a site access road to the jetty, site-wide services, mine infrastructure area facilities, a product stockpile and process plant pad.

Potential Job Creation
Not stated.

Net Present Value/Internal Rate of Return
The project has a pretax net present value, at an 8% discount rate, of A$290-million and an internal rate of return of 34.9%, with a payback from the start of production of 3.9 years.

Capital Expenditure
Initial capital expenditure is estimated at A$79.4-million.

Planned Start/End Date
Not stated. Diatreme has the updated DFS is under review as it assesses synergies with the Northern Silica Project and advances the project through the Cape Silica Holdings JV structure.

Latest Developments
Diatreme announced on April 13, 2026, that its wholly owned subsidiary, Metallica Minerals, had entered into a binding share sale agreement with Cape Silica Holdings to sell Cape Flattery Silica in exchange for additional shares in the JV. The transaction values the project at A$26.01-million. 

Diatreme has said the transaction will streamline ownership of its Far North Queensland silica sand assets, consolidate project costs, support focused community engagement and advance the development pathway for its regional silica projects. 

Sibelco Silica, which holds 26.8% of Cape Silica Holdings, will subscribe about A$5.1-million for shares in the JV on completion and has been granted an option to subscribe for a further A$4.4-million before July 7, 2026. 

Diatreme has said this will generate about A$7.4-million of additional funding for the JV, before costs and any applicable stamp duty, and will also reimburse Diatreme about A$2.1-million in acquisition-related costs. 

The transaction remains subject to shareholder approval and other conditions precedent. If completed, and assuming Sibelco exercises all its options, Diatreme’s interest in Cape Silica Holdings will remain at 73.2%.

Key Contracts, Suppliers and Consultants
Not stated.

Contact Details for Project Information
Diatreme Resources, Neil McIntyre, tel +61 7 3397 2222 or email manager@diatreme.com.au.