2012 Group Technical Report GR159/10, MLN 2, MLN 3, MLN 951, MLN, 952, MLN 953, MLN 956, MLN 957, MLN 958, MLN 959, MLN 960, and MLN 961

Abstract

Groote Eylandt is Aboriginal-owned land, as granted under the Aboriginal Land Rights (NT) Act 1976 (ALRA). The Groote Eylandt Mining Company Pty Ltd (GEMCO) has its obligations defined in various lease documents including Mineral Leases and Special Purpose Leases (SPLs), a Letter of Understanding dated 13 May 1965 and an Agreement dated 16 September 2006. Groote Eylandt is predominantly composed of a stable basement of Proterozoic quartz sandstones and quartzites. The overlying manganese deposits are part of a blanket of Cretaceous sediments lapping onto the western margin of the Proterozoic basement sandstones and quartzites of the McArthur Basin. The manganese orebody is a sedimentary layer, consisting of manganese strata occurring between clay and sand beds and gently undulates beneath the western plains of the island. It extends over an area of about 50 square kilometres as an almost continuous horizon ranging in thickness up to 11 metres. The ore body is thus essentially stratabound and strataform in character. Resource definition drilling was undertaken during FY12 (covering the period July 1 2010 to June 30 2011) with the purpose of increasing confidence in the existing Mineral Resource and converting previously unclassified mineralisation. A total of 124 Reverse Circulation (RC) holes were drilled for a total of 3,726m in lease areas MLN 959 and 960. For these drillholes, 1,496 samples were collected for analysis. Unfortunately, the program was impacted by a later than planned start, poor drill rig availability, and an early wet season. As a consequence only 22% of the planned holes were completed (from a total of 560 drillholes). During the reporting period, aerial photography flyovers were also completed over the mining leases to generate additional survey control and facilitate the reconciliation of ROM and product stockpiles.