The Kooline Project is centred 55 kilometres south of the Paulsen’s goldmine and 190 kilometres WNW of Paraburdoo within the Ashburton province of Western Australia. The project area tenements consist of granted: Exploration Licences, E08/2372, and E08/2373 and ELA 08/2956 (Figure 1) and covers a total of 386 km², and more importantly, includes 48km of contiguously striking licences linking a number of clusters of historic artisanal lead workings and mines.
Figure 1: Kooline Project Location
The Kooline Project is situated in a relatively underexplored region in Western Australia where numerous historic gold, and particularly lead workings are evident. The tenements strike along a moderately defined magnetic and gravity anomaly, indicating the potential presence of moderately deep igneous intrusions. Such intrusions are an important heat source driving the circulation of hydrothermal fluids enriched in various base and precious metals, particularly lead. The lead is deposited in vein filled shears and structures as massive galena (Figure 2) In addition, a number of other base metal anomalies occur within the project area with numerous high-grade copper, lead, silver and gold samples from rock-chipping and RC drilling.
Figure 2: Massive galena from the Bilrose mine Kooline Lead/Silver Field
The Ashburton River area, particularly around Mount Dawson, was actively mined for alluvial gold in the late 1890’s. This interest in the area faded with the discovery of the Golden Mile in Kalgoorlie. However, despite its remote location the high-grade massive galena deposits of the Kooline lead were attractive targets for historic mining operations. Production commenced there after the Second World with the first lease in the field was pegged over the Beadon mine in October 1947 and mining continued until 1959 when low metal prices forced the mines to close.
Over 40 workings can be found in the area and although most of these operations were small-scale “hand-mined” shallow workings generally no deeper than 15 metres. Three of the mines accounted for over 60% of production, these being the Gift, June Audrey, and Bilrose mines, each with its own battery or crusher and a concentrator. The Gift mine was the most substantial operation reaching a depth of 52m and workings that extended for almost 50m east and west from the shaft.
Output from this time yielded some 2,679 tonnes of lead, and 26,522 ounces of silver with an average grade of 10-12% lead and 30-45g/t silver. A proportion of the mined ore was sufficiently high enough grade for direct shipping.
Most of recent exploration activity over of the licence areas at Kooline was undertaken between 2007 and 2010 and included a number of geophysical and geochemical field surveys and some very limited drilling.
In 2008, a series of gradient array IP surveys over the Pharlap June Audrey and Silver King/Rainbow historic mines and identified several conductive zones with considerable strike length. Additional Dipole-Dipole surveys across the June Audrey and Silver King/Rainbow workings identified strongly conductive bodies at depth.
Whilst some anomalies were tested in a limited 10-hole RC drill programme at that time, many targets remain untested. These untested targets include zones of conductivity evident from IP surveys with coincident moderate to strong auger soil geochemical anomalies. Some of these targets are below the deepest levels of workings, or where mineralisation extends beneath areas of transported colluvium and alluvium.
Also of interest is an anomalous gold intersection from this drill programme where hole AK09RC04 at the Bilrose mine workings (Figure 3) unexpectedly returned a 1m intersection @3,87g/t from 25 metres depth (AHN.ASX September Qtrly 30/10/2009) No follow-up testing was undertaken.
Figure 3: Bilrose Mine area Kooline
The cluster of over thirty mines at Kooline has seen rock-chip samples containing galena cerussite and silver returning some extremely high grades. A number of rock chip samples were collected from the main areas during the March 2018 field trip by geological consultants Unearthed Elements. The assay results obtained from these samples in the June quarter continue to confirm the high grade nature of the mineralisation with results up to 79% Pb and 232g/t Ag. The significant sample results are shown in Table 1 below:
|KRK005||55.3||249||615||0.11||Bilrose - costean|
|KRK007||7||39||150||0.03||Bilrose channel sample 1m|
|KRK008||79.3||232||1390||0.21||June Audrey - spoils pile|
|KRK011||44.7||40||690||0.05||Big Chief - costean|
Due to the high grade in the samples all were re-analysed using XRF in order to provide a more accurate determination of the lead grade. It is notable that all the samples carried anomalous gold and copper values.