Eclipse Metals' (NYSEMKT:EPM) petrophysical testing indicates that primary mineralisation at the historical Amamoor and Upper Kandanga manganese mines within the Mary Valley Project located 15 kilometres south of the town of Gympie continues at depth.
The testing was done to better understand and measure manganese mineralisation in the area of historic workings.
Mary Valley had historic production of over 31,000 tonnes of ore grading a very high 42% to 51% manganese from mining operations carried out during the 1920's and 1960's.
Recent rock chip samples collected from the Amamoor workings returned high grade assays up to 52% manganese and from the Upper Kandanga prospect up to nearly 41% manganese.
Within the three tenements comprising the project there are at least 22 occurrences of known manganese mineralisation - hinting at the potential within the project area.
Given this, there is substantial exploration upside with geological evaluation of old reports over historic workings indicating the potential for significant tonnages of siliceous manganese ore.
The testing suggests that ground based IP/ Resistivity surveys will be an effective exploration method to define blind mineralisation along strike from and at depth below known mineralised zones.
A detailed low-level airborne magnetic survey could also be an effective tool to indicate zones of potential manganese mineralisation in areas of rugged terrain with dense vegetation.
The petrological examination supports classification of the mineralisation style as Cuban-type of Volcanogenic Manganese Deposits. Most of the mineralisation consists of primary manganese minerals such as hausmannite.
It has also mapped the geological control of mineralisation and identified potential for at least 167,000 tonnes of high grade manganese mineralisation.
Petrophysical and Petrological Testwork
Seven samples of rocks, representing mineralisation and barren host rocks were submitted to Southern Geoscience Consultants for comprehensive petrophysical testing.
An additional eight samples were tested for magnetic susceptibility and conductivity.
Three of the samples subjected to comprehensive petrophysical testing were also sent to Townend Mineralogy Laboratory for petrological investigation (table below). These samples were selected to represent low to high grade manganese mineralisation from the Amamoor and Upper Kandanga historical mine areas.
The petrophysical testing found that manganese mineralisation is significantly more magnetic, dense and is non-conductive compared to the surrounding country rocks.
It indicates that a low-level, close line-spaced air-borne magnetometer survey by fixed-wing aircraft is likely to be the most cost-effective initial method of remote sensing exploration.
Follow-up IP/resistivity surveys, which recognise robust contrasts between low to average and high grade manganese mineralisation, could be highly effective for mapping mineralised systems in areas indicated by the airborne magnetic survey.
The fact that some manganese mineralisation is strongly magnetic will be of great assistance in evaluating the potential of some prospects such as Amamoor West, Skyring Creek and Eel Creek.
Petrological investigation has found that exposed remnant mineralisation is mostly primary which is supported by field observations.
As a result, the grade range of samples collected from the workings are likely to be representative of the grade of mineralisation continuing at depth at both Amamoor and Upper Kandanga.
Mary Valley Manganese Project
The Mary Valley Manganese Project offers Eclipse the opportunity to identify additional mineralisation in largely under-explored tenements with historic production.
Despite historical production, little to no geological activity has been recorded over the Mary Valley prospects for manganese in the past 50 years.
Historical Amamoor manganese mine workings constitute a brownfields project with potential for readily mineable mineralisation on or near surface.
Old waste dumps and stockpiles could provide bulk samples and possibly saleable ore to evaluate potential for full-scale mining.
To date Eclipse has only examined a small part of the high grade mineralised areas within the overall project.
Another six historic mined areas are yet to be geologically assessed with the objective of delineating larger potential resources of manganese mineralisation than apparent from historical production.
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