Annual report on MC 24456 Mt Shoobridge Pyromorphite

Abstract

Exploration was carried out in a quartz filled shear zone containing small pods of lead and zinc sulphide mineralisation in Burrell Creek Formation. The target mineral of potential economic interest was the mineral Pyromorphite, which is common on the old waste rock dumps of the prospect. An excavator was bought in for a day on the 26 July 2010 with a target of 4 to 5 trenches. Only one trench was dug. There was 2 hours of machine breakdown time and it was found that the iterative process between machine operator and geologist was more time consuming than expected. There was no narrow bucket accompanying the machine at the start of the exercise or a ripper to deal with the hard quartz lenses. This matter will not arise in 2011 when it is aimed to complete the program with appropriate machinery. The trench that was successfully dug located at a depth of 2 metres a ~1 metre long by 15cm wide lense of lead and zinc sulphide mineralisation enclosed by an iron coloured clay exterior. The lense was encapsulated partly in quartz. Small crystals of Pyromorphite were located in the clay and attached to oxidising parts of the sulphide mineralisation. The near surface sulphide mineralisation is indicative of either a retarded oxidation process of unknown chemistry or a short period of oxidation. The Pyromorphite mineralisation was not obvious upon initial removal from the trench and was distinguished by the specific gravity of the clay portion. The optimum target is at least a 0.5 cubic metre mass of Pyromorphite. Such a mass could produce sizeable commercial xtyls of Pyromorphite. Hence the target is quite small as far as standard mineralised targets go. The quartz matrix for the sulphide mineralisation and the small size of the sulphide mineralisation suggests that the oxidation process at the site it not likely to produce classic volumes of Pyromorphite such as found in the oxidation system at the Browns project near Batchelor. The mine still has potential for lower value 'location' specimens. One cubic metre of excavated quartz and mineral vein material was placed on a surface of old waste rock dump material beside the rehabilitated trench. It contains some Pyromorphite in thick clay and some primary galena and sphalerite, with minor cerussite. Trace copper was found in the form of small malachite coatings on galena. This rock and some larger coherent pieces on the edge of the excavation provide geological and mineralogical information for the project and any future explorers. There were no outstanding specimens of Pyromorphite collected from the trench. Nevertheless, for the specimens that were found, laboratory cleaning may be able to remove the iron clay and retain the Pyromorphite xtyls on the remaining matrix of siliceous iron oxide, and in some case a matrix of fine Pyromorphite. To this end some 16 specimens will be forwarded to a specialist mineral cleaning laboratory in Texas, USA. Commercial assessment of the specimens will follow this cleaning exercise which will be viewed by the writer in the USA in February 2011. The second leg of commercial assessment is the completion of the original approved trenching program.