Looks like the RIO deal with Cadelco was for Marcunga which they bought from LPI. Looking at historical announcements from LPI it had around 2.15m LCE worth of resources indicated when it was acquired.
Cadelco would have done significant work since then. LPI was looking to produce 15k tonnes to 20K tonnes of LCE per year over 20 years and Cadelco acquired LPI for A$385m in OCT 23 and now Rio Tinto is paying $900m over several years for 49.99% after 18 months.
Mind you asset is in Chile and not in USA and with current administration looking to kick start mining of battery and critical minerals under "drill baby drill" and listed companies that are currently drilling or close to drilling in USA seeing there value go up due to improved interest and sentiment in USA around mining, this is all looking positive currently GLTAH
