2014 Group Technical Report GR159-13, MLN 2, 3, 951, 952, 953, 956, 957, 958, 959, 960 and 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. A number of drilling campaigns were conducted during the reporting period. To increase the confidence in the resource and to convert resource into reserve, a reverse circulation (RC) resource definition drilling program was carried out, with a total of 345 RC holes were drilled for 7,296m. Diamond drilling was carried out in order to update geometallurgical assumptions and to develop a short term mining model. A total of 112 diamond holes were drilled totalling 1,526m. Minor drilling and soil testing was also conducted for the installation of environmental ground watering bores, 11 holes were drilled totalling 87 metres. In addition, geotechnical core drilling was completed to test ground conditions for a new tailings storage facility. A total of 15 holes were drilled totalling 251m. Two aerial surveys were conducted in order to update mapping information, reconcile stockpile volumes and for elevation control on the mine site.