Fourth Combined and Final Report for the period 15 October 2019 to 20 February 2020 EL 24389 Cato Plateau 2, EL 4171 Cato River and EL 4170 Cato Plateau GR077 Cato Project

Abstract

EL 4170 Cato Plateau and EL 4171 Cato River were applied for by BHP Minerals Pty Ltd (BHP) on 3rd December 1982. EL 4170 was granted on 14th October 2004 and EL 4171 was granted on 12th September 2005. EL 4170 was renewed untill 13th October 2020 and EL4171 was extended until 11 September 2019. EL 24389 was granted on the 23rd of June 2016 for a period of 6 years which would have taken it until the 22nd of June 2022. RTX signed an agreement with BHP on 27th March 2000 whereby RTX took over management of EL 4170 and EL 4171 (the tenements). This agreement was amended in 2007 to allow for BHP to conduct simultaneous activities for manganese within the licence package. GEMCO (a subsidiary of South32) are the responsible party for the agreement. GEMCO transferred ownership of EL 24389 to RTX on the 10th of May 2017. Combined reporting of EL 4171, EL 4170 and EL24389 was granted in June 2017 and the project called 'Cato Project' with reporting number GR077. The Cato Project formed part of the larger contiguous tenement package in east Arnhem Land, which was considered prospective for bauxite and manganese. These three licences (Cato project) cover the Cato plateau, which is a known occurrence of bauxite within the east Arnhem area. GEMCO, under the agreement with RTX, retained the right to explore for manganese on EL's 4170, EL4171 and 24389. When EL 24389 was granted on 23 June 2016 (for a period of 6 years), the bauxite targets identified from the data review were prioritised. A program of work was developed and executed to drill test the priority bauxite targets on EL 24389 and accessible parts of the main plateau on EL 4170. Follow up work to the drilling program included desktop assessment of the reported assay results and mineralogical estimates and a bulk sampling program to test the benficiation potential of the identified bauxite. Follow up work aimed to identify the potential quality of the bauxite present and its spatial distribution across the plateau. Subsequently to these work programs, it was determined that no economically viable resource of interest to Rio Tinto could be defined within the Project and hence the decision was made to surrender the tenements in full.