A total of four deposits comprise the Jervois Base Metal Project, namely Marshall-Reward (including Reward East and Sykes), Green Parrot, Bellbird including Bellbird North and Rockface. The current round of work involved updated resource estimates that included new drilling for Rockface and Reward and the cut-off grade being doubled to 1% copper for copper resources below 200mRL that are assumed to be accessible by underground mining rather than from an open pit.
When compared to the 2015 resource estimate the 2018 resource update has increased total contained copper by 18% to 384,800 tonnes. The overall copper grade has increased by 43% to 1.53% copper. Associated silver grade and contained metal have also increased by 27% and 4% respectively. (Figure 1 &2)
The new resource estimate for Rockface is based on a total of 509 1m composites for all the Rockface lodes that were extracted from the drillhole database constrained by the mineral wireframes. The HW Main Lode comprised the dominant number of data points at 306. At Reward a total of 2,859 1m copper composites were extracted from the drillhole database. Unfortunately, due to the longevity of the historical exploration some of the earlier drilling did not analyse for gold and silver rendering a lower number of composites compared to copper, this is particularly evident for gold (2,218 composites). A top cut of 6g/t was applied to the gold grades from Reward affecting seven samples resulting in a 10% drop in the mean value for the composites.
Modelled gold grades have been included as part of the Marshall-Reward, Rockface and Bellbird (including Bellbird North) resource estimates. Gold Mineral Resource Estimates are reported for the relevant copper cut-off grade on blocks with its centroid inside the mineral wireframe. The Reward UG deposit has lead resource blocks excluded and an upper elevation limit of 200mRL. The Bellbird UG Mineral Resources are reported from the 2015 model using a 1% copper cut off and a 200mRL upper elevation limit. The Bellbird and Marshall-Reward OP deposits are reported from the 2015 models at a 0.5% copper cut off and have a basal limit of 200mRL.
A global gold Inferred Resource for the three deposits stands at 20.5Mt at 0.23 g/t totalling 154,200oz.
Exploration Potential* for the copper mineralisation comprises peripheral blocks to the defined resource estimates within the interpreted mineral wireframes and amounts to:
0.3 to 0.5Mt @ 2 to 2.5%Cu, 0.1 to 0.15g/t Au, 10 to 15ppm Ag for Rockface and
2 to 2.5Mt @ 2 to 2.5%Cu, 0.5 to 1.0/t Au, 35 to 50ppm Ag for Reward.
The lodes are open at depth, and there are additional possibilities along strike from the deposits based on isolated drill hole information and from interpretations of the geophysical surveys.
* The potential quantity and grade of the Exploration Target is conceptual in nature and there has been insufficient exploration to define a Mineral Resource. It is uncertain if further exploration will result in the determination of a Mineral Resource.
Table 1. 2018 Jervois Resource estimate (these tables may contain minor rounding errors).
(OP - lower elevation limit of 200mRL, UG - upper elevation limit of 200mRL )
* The lead-zinc resource estimates from 2015 remain unchanged, not having been reviewed because exploration focus has been entirely on copper.
**Including the copper mineralisation associated with the lead/zinc resource estimates
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