Ioneer boosts South Basin lithium carbonate resource by 168% at Rhyolite Ridge

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By Lorna Nicholas - 
ioneer ASX INR Rhyolite Ridge South Basin mineral resource lithium boron Nevada

Contained lithium carbonate equivalent at Rhyolite Ridge now totals 3.4Mt.


As it progresses towards development, Ioneer (ASX: INR) has revealed a 168% increase to contained lithium carbonate resources for the South Basin deposit within its Rhyolite Ridge project in Nevada in the US.

The updated resource now totals 3.4 million tonnes of lithium carbonate equivalent – up from 1.2Mt in the previous estimate.

Contained boric acid equivalent has also grown from 11.9Mt to 14.1Mt.

Ioneer noted the updated resource comprises both high-boron lithium mineralisation and low-boron lithium mineralisation, compared to previously which was solely high-boron lithium mineralisation.

The resource also lies within the project boundary, where Ioneer has applied for mining permits.

It also offers optionality over future growth opportunities including boosting lithium production, without increasing boron output.

All mineralised units at the South Basin deposit remain open in three directions.

The resource accounts for about 3 square kilometres of the entire South Basin target area. About 60% of South Basin remains to be drilled – affording considerable upside.

Additionally, 80% of the resource is classified as measured and indicated, with about 44% considered high-boron lithium mineralisation and 56% as low-boron lithium.

Commenting on the updated estimate, executive chair James Calaway said it was a “significant increase”.

“It highlights Rhyolite Ridge’s optionality and multi-generational scale potential to provide a secure, sustainable, and reliable domestic source of lithium for the growing electric vehicle battery supply chain.”

Ioneer also plans to test the North Basin target within the project which covers 14sq km.

Developing Rhyolite Ridge

Ioneer managing director Bernard Rowe said the company to-date had focused heavily on progressing development plans for Rhyolite Ridge.

“With binding offtakes in place, debt and equity commitments of nearly US$1.2 billion and the project in the final stage of permitting, we can now begin demonstrating the broader scale potential at Rhyolite Ridge.”

“The updated mineral resource base for the South Basin is a fantastic start and we look forward to building on this further with significant growth potential through South Basin extensions as well as increased exploration efforts on the mineralised and much larger North Basin,” Mr Rowe added.

Production at Rhyolite Ridge is forecast at 22,000t a year, with boron output of 17,400tpa over 26 years.