ASX-listed Viridis Mining & Minerals has upgraded the mineral resource estimate (MRE) of its Colossus rare earths project, in Brazil, following targeted infill drilling.

The measured and indicated MRE of the project is now an industry-leading 305-million tonnes grading 2 723 parts per million (ppm) of total rare earth oxides (TREO) and 659 ppm of TREO, respectively.

Notably, the programme identified a measured mineral resource of 31-million tonnes grading 2 858 ppm TREO and 758 ppm mixed rare earth oxides (MREO), providing the company with a high-confidence resource foundation for the highest-value years of planned production supported by outstanding project economics, strong early cash flows and rapid capital payback.

Viridis reports the Colossus mineral resource totals 473-million tonnes grading 2 505 ppm TREO and 592 ppm MREO. High value magnet rare earths continue to comprise 24% of the TREO within the measured and indicated resource.

Viridis says the substantial measured mineral resource supports an anticipated conversion of the initial production schedule to proven ore reserves as part of the project's definitive feasibility study. This satisfies a key requirement for project debt financing and represents a major step towards a final investment decision on the project during the second half of the year.

"The Colossus project continues to set the global benchmark for ionic adsorption clay rare earth developments through its combination of world's highest-grade measured and indicated MREO mineral resource, industry-leading measured resource grade supporting the early years of planned production, proven reserve conversion pathway supported by exceptional geological confidence, industry-leading metallurgical recoveries using a near-neutral pH leach process and significant potential for further resource growth," explains Viridis MD Rafael Moreno.

Moreno mentions that the current MRE covers only 12% of Viridis' landholding, however, Colossus already hosts almost half a billion tonnes of mineralisation and the world's highest-grade measured and indicated MREO resource.

"This is not just a geological milestone, it is a financing milestone. Defining more than five years of measured resources for the initial mine plan satisfies a key technical requirement for project debt financing," Moreno says.