Great Boulder is exploring the project under an earn-in agreement with Ausgold Limited. Post the end of FY19 the Company has a 51% interest in the project, with the aiming of moving to 75%.
Ausgold previously identified a number of conductive anomalies at Winchester from airborne and ground electromagnetic (EM) surveys. Initial aircore drilling at the Winchester Prospect resulted in the discovery of significant copper and nickel sulphides, including:
- 48m @ 0.6% Cu and 0.3% Ni, including 9m @ 1.1% Cu and 0.4% Ni; and
- 39m @ 0.4% Cu and 0.2% Ni.
In late 2018 the Company drilled its first RC holes into the Winchester Prospect at Winchester, as well as a regional aircore program designed to increase the understanding of local stratigraphy and geochemistry. The holes intersected primary sulphide mineralisation, with significant intersections including:
- 7m at 1.1% Cu, 0.2% Ni, 0.01% Co, 0.19g/t Au, 0.13g/t PGE from 120m (18WNRC001)
- including 2m at 1.8% Cu, 0.2% Ni, 0.02% Co, 0.25g/t Au, 0.22g/t PGE
- 13m at 0.9% Cu, 0.3% Ni, 0.02% Co from 138m (18WNRC002);
- including 5m at 1.1% Cu, 0.7% Ni, 0.04% Co, 0.10g/t PGE.
Sulphide mineralisation at Winchester is of higher nickel tenor than the other regional projects, demonstrating the potential to achieve grades of 3% nickel in massive sulphide. Drilling will continue to target strike and dip extensions to mineralization at this prospect.
In 2019 118 aircore holes were drilled for the purposes of mapping the regional stratigraphy and geochemistry. Downhole assay results identified a significant zone of coincident nickel, copper and PGE anomalism over a strike extent of almost 3km, extending from the Winchester prospect down to the southern boundary of the tenement.
Great Boulder also completed a ground gravity survey at Winchester to assist with geological interpretation, with station intervals of 200m on lines 400m apart. This information will be used in ongoing modelling and drill targeting.
The Company intends to continue exploring the Winchester Project, with an emphasis on extending known mineralisation at the namesake Winchester prospect with additional RC and diamond drilling.
AC drilling over aeromagnetic inversion model (pink) and gravity inversion model (green) surfaces. Left image displays AC collars coded by colour (Ni) and contour (Cu,PGE) for the maximum values intersected downhole while the right image displays the assay value of the bottom of hole sample.