Mineral sands developer Diatreme Resources on Monday announced a mineral resource estimate upgrade for the Si2 deposit, part of its Northern Silica project in north Queensland.

The Si2 deposit now hosts a total resource of 272.5-million tonnes at 99.21% silicon dioxide, with low levels of impurities, reinforcing its potential to supply premium silica sand to high-end markets such as PV glass manufacturing.

“This major resource upgrade reinforces the outstanding potential of our Northern Silica project. We have more than confirmed the scale and purity needed to support a long-life mining operation targeting PV silica markets,” said Diatreme CEO Neil McIntyre.

“With permitting and testwork under way, and a prefeasiblity study (PFS) next on the agenda, we are building the foundations for an exciting new silica sand supply chain out of Cape York with decades of mine life.”

The resource estimate includes a 278% increase in the measured category, which now stands at 187.5-million tonnes, and lifts the total resource by 16% from the previous 235-million tonnes. The updated estimate is based on a refined bulk density of 1.65 t/m³ and confirms a homogeneous particle size distribution, ideal for downstream processing into high-purity silica products.

Located in the world-class Cape Bedford–Cape Flattery dune field and adjacent to the Port of Cape Flattery, the project benefits from strategic proximity to export infrastructure and global markets.

Diatreme said the new resource provides the necessary geological confidence to underpin mine planning, paving the way for completion of a PFS and the establishment of ore reserves.

In parallel, the company is advancing environmental permitting with detailed assessments ongoing ahead of the environmental-impact statement submission scheduled for the third quarter of 2025. Metallurgical testwork is also ongoing to finalise product specifications, after which Diatreme plans to initiate offtake discussions with targeted customers in the silica sand market.

Combined with its other holdings across the Cape Flattery and Cape Bedford areas, Diatreme now boasts a global resource exceeding 500-million tonnes, positioning the company as a leading player in the emerging high-purity silica sector.