EPM 14185 and Pinnacles Prospect
EPM 14185 is comprised of five separate sub-block groups, which are located in Silver Valley, Mount Garnet and Crystalbrook localities, North Queensland.
The Pinnacles prospect is located within EPM 14185 (sub block group 1), approximately 34 km south-southwest of Ravenshoe, in the Silver Valley locality, North Queensland. Pinnacles is approximately 105 km south-west of Cairns and can be accessed off the Kennedy Highway via cleared tracks on Woodleigh Station and Coolgarra Station.
The Pinnacles deposit is a collection of over 20 individually identified deposits of various sizes located within EPM 14185. These were identified during the early 70’s by Comalco during an exploration campaign targeting fluorine. Consolidated tin later focused further exploration work around the Pinnacles area looking for tin, iron, and fluorine.
The deposits sit within a roof pendent of carbonate rich Chillagoe Formation with dimensions of 3.5 km north south by 500 m east–west. The 23 prospects include Queens Birthday, Citriodora, Censorship Hill, South Wafer, Wafer, Toledo, Hastings, Harthog, Llahsram, Sniksa, Far North, Michael and Harrison. The prospects are interpreted as a series of irregular skarn lenses within the roof pendant of Chillagoe Formation rock, surrounded and underlain by the intruded Coolgarra Granite, a member of the O’Brien’s Creek Supersuite.
Initial modelling of the Pinnacles deposit was undertaken by Optiro in 2013 based on drilling undertaken by Consolidated Tin Mines in 2012. Early exploration work undertaken in the 1970s by Comalco was not used in this MRE. The CSD MRE utilised tin (Sn) as the controlling elemental parameter with Metal Equivalents (ME) calculated for iron (Fe) and fluorine (F).
Pinnacles is a large lower grade tin resource which contains substantial amounts of fluorite. Mineralogy shows the fluorite is fine grained and closely associated with other minerals, mainly Epidote. Metallurgical testing has been conducted to remove the fluorite to another product. The processing of Pinnacles ore would involve fine grinding (30 microns) then removal of the majority of the fluorite to a marketable fluorite flotation product. After removal of the fluorite the treatment to recover the tin and iron would be identical to that proposed for Gillian and Windermere and so it could be treated via the same process.
EPM 14185 is a very large EPM and is underexplored. There is numerous tin, tungsten, copper, and fluorite across its extent.