Supply Chain Risks Mount as Castile Controls Rare Australian Bismuth Resource

Strategic Addition to Rover 1 Project

Castile Resources (ASX: CST) has announced a significant update to its flagship Rover 1 project by incorporating critical mineral bismuth as a by-product in its Bankable Feasibility Study (BFS). This move comes amid a remarkable surge in bismuth prices, which have skyrocketed over 500% in recent weeks, driven largely by Chinese export restrictions.

Mark Hepburn, Managing Director of Castile Resources, highlighted the strategic importance of this addition, noting that the company now controls one of the very few bismuth Mineral Resources in Australia, totaling approximately 5,900 tonnes. This positions Castile at the forefront of bismuth development in a market where supply chain security is increasingly critical.

Bismuth Market Dynamics and Supply Constraints

Bismuth is gaining recognition as a strategic metal with diverse applications spanning defense technologies, rocket propellants, thermoelectric devices, fire suppression systems, and emerging nuclear reactor designs. Despite its growing importance, global supply remains highly concentrated, with China accounting for roughly 80% of production.

Recent Chinese export restrictions, announced in February 2025, have imposed new tariffs and require explicit permission for overseas sales of bismuth, further tightening global availability. This has sent prices soaring, with bismuth trading as high as US$55 per pound in the United States and around US$35 per pound in European markets, translating to approximately A$192,500 per tonne.

Minimal Capital Impact, Maximum Strategic Value

Importantly, Castile’s BFS indicates that the capital expenditure required to incorporate bismuth recovery into the existing Rover 1 processing infrastructure is minimal. This suggests that the company can capitalise on the bismuth price surge without significant additional investment, enhancing the overall project economics.

Historically, Australia has not been a major producer of bismuth, with production ceasing decades ago despite the Tennant Creek region’s past output. Castile’s resource thus represents a rare and valuable opportunity to develop a stable, western-sourced supply of this critical mineral.

Geopolitical and Market Implications

The addition of bismuth to Rover 1 underscores the growing geopolitical risks surrounding critical mineral supply chains. With China’s dominant role and recent export controls, western markets face increased pressure to secure alternative sources. Castile’s resource could become a key component in diversifying supply, particularly for defense and emerging technology sectors.

While the timing and scale of commercialisation remain to be fully defined, this development marks a pivotal step in enhancing the value and strategic relevance of the Rover 1 project.