Hillgrove Resources Limited Announces Updated Nugent Mineral Resources Estimate
underground copper mine1. All diamond drill holes drilled by HGO to 31 March 2022 have been used to estimate the block grades in this MRE.
Grade control data have not been used in the estimation of the spatial continuity or grade estimates. The open
pit grade control data have been used to assist the interpretation of the general trends of the mineralised zone.
Core recovery is excellent with 98% of all mineralised core intervals recording >98% core recovery.
Unsampled intervals have been assigned zero Cu, Au, Bi, Ag values and then the drill hole samples composited to
1 metre downhole lengths from drill hole collar for all data analysis and estimation.
The drill hole data and geology therefrom have been used to interpret a wireframe of the Nugent Lode system.
The Nugent lode system is a single lode system within which two Cu zones occur. There are additional Cu, Cu-Au
and Au only vein sets in both the Hangingwall and Footwall of the wireframed Nugent lode (for example, KTDD230
14.5m @ 1.6% Cu, 0.34 g/t Au from 252.2m downhole), but these have not been wireframed due to a lack of
drilling data and geological understanding of their continuity.
Variography of the Cu mineralisation has been modelled and a Multiple Indicator Kriging algorithm applied to the
composited data using the wireframe of the Nugent Lode as a hard boundary for the kriging search algorithm.
The search strategy is a weighted ellipse oriented at -72 deg to 130 deg (dip/dip-direction). Panels are 2m (east)
by 15m (north) by 20m (elevation) and are oriented along the strike of the mineralisation at 040deg. In each panel
the proportion of the panel above the 0.7% Cu cut-off grade is estimated, and the Ag, Bi, Au grade above the
relevant Cu COG is also estimated. Indicated Resource panels are only located within the wireframed main Nugent Lode and have been estimated
from 20 composites within four quadrants within an ellipse of 7m (across-strike) by 60m along-strike and 85m
down-dip. Inferred panels are estimated where the same search strategy only locates 10 composites within two
quadrants. Gold, silver and bismuth have been estimated assuming a reasonably strong correlation with copper.
All the mineralisation is in fresh rock and an average bulk density has been estimated from 341 drill samples. The
average bulk density of the Nugent Lode samples of 3.0 t/m3 has been assigned to all blocks (which is consistent
with the bulk density when open pit mining of higher-grade material). Figure 2 is a longitudinal section and Figure 3 is a set of three cross-sections through the Nugent mineral system showing the MIK panels coloured by classification against the HGO diamond and RC drilling used in the estimate.
The sections indicate that the MIK method has appropriately modelled the copper mineralisation and its geologic
uncertainty. Figure 4 shows the tonnes per 20 metre elevation through the entire Nugent mineral system and shows that
further drilling below 980 RL is required to continue to grow the resource. Summary: In summary, the July 2022 Mineral Resource Estimate for Nugent has demonstrated that the infill and extensional diamond drilling undertaken from 2020 to 2022 has significantly increased the size of the total resource and effectively reduced the uncertainty in the resource. The updated Nugent resource will now be able to be incorporated into an updated assessment of the economic viability of an underground mining operation at Kanmantoo.