RTN was incorporated on July 15, 1969 to develop the nickel ore deposits discovered at the Rio Tuba mine site in 1967. It was granted rights over the Rio Tuba property in 1970 and commenced mining in 1975. RTN made its first commercial shipment in 1977. RTN’s mining authority at Rio Tuba derives from an MPSA No. 114-98-IV Amended initially covering an area of 990 hectares for the first 25-year term. The MPSA was then amended on October 28, 2019, to include an area covered by a separate MPSA application, thereby increasing the area to an aggregate of 4,538 hectares. On December 2, 2021, the MPSA renewal application of Rio Tuba was approved by the MGB and a fresh 25-year MPSA term, commencing on October 8, 2021, was granted subject to the issuance by the National Commission for Indigenous Peoples (NCIP) of a Certification Precondition.