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2003 News Archive

Discovering manganese ore under cover using ‘hoistem’

Jayson Meyers - April 2003

LEME research has lead to the discovery of several new manganese ore bodies in the Woodie Woodie manganese mine corridor, located in the Pilbara region of Western Australia. The Woodie Woodie Mine is owned and operated by Pilbara Manganese Limited, a subsidiary of Consolidated Minerals Limited, who sponsored this project. High-grade manganese ore is mined by Pilbara Manganese using open cut methods, and the ore is shipped by truck to Port Headland for export around the world where it is primarily used to make steel.

Manganese was discovered at Woodie Woodie over 50 years ago, and has only been mined on a large scale by Pilbara Manganese over the last five years. The geologists at Pilbara Manganese recently recognized that the manganese ore is deposited from hydrothermal solutions into ancient dolomite sedimentary layers that are 2.5 billion years old. The ore deposits sit in fault and pipe like structures within the dolomite, and they may not always come to the surface. Some ore bodies are also buried by glacial sediments from the Permian period, about 250 million years ago, and younger sedimentary deposits. For these reasons, this project sits under LEME Program 2, Exploration Under Cover.

Click for larger imageAt the recommendation of LEME researchers, an innovative time-domain helicopter electromagnetic system called Hoistem was employed to explore for buried manganese ore bodies previously missed by other geophysical prospecting methods. The hoistem system is under development by Newmont Mining and GPX Airborne, and was used at Woodie Woodie as part of an ongoing R&D project run by Pilbara Manganese and the Curtin University Exploration Geophysics Department in association with the CRC-LEME. The Hoistem system works like a flying metal detector that looks for conductivity changes in the ground, such as conductive manganese ore in a resistive dolomite.

Click for larger imageFollowing supervision of logistics and parameter testing at site, the data were processed by LEME researchers using innovative methods to enhance the response of conductive manganese targets and to separate this response from other conductive features, such as saline groundwater and clay filled drainage valleys. A number of the targets were drilled and about five new manganese prospects were discovered just within the northern part of the Hoistem survey, with more targets to be drilled occurring in the south. One of these ‘blind discoveries’ has turned out to be the largest single manganese ore body found to date in the Woodie Woodie corridor, having a resource of 1.6 million tonnes. It sits under 20 metres of Permian clay and was named ‘Chris D’ after a former company director (figures 1 and 2). Chris D and other hoistem discoveries have increased Pilbara Manganese’s resource base and extended the mine life by several years.

Research is continuing on the geophysical nature of manganese mineralisation and ore forming processes, and the application of innovative geophysical methods for further exploration success. This project is supervised by LEME researcher Dr. Jayson Meyers and LEME PhD scholarship recipient Anousha Hashimi, both from Curtin University Exploration Geophysics.


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CRC LEME is established and supported under the Australian Government's Cooperative Research Centres Program. The CRC Program is an Australian Government initiative which brings together research groups with common interests.

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