Orion Minerals Ltd (ASX:ORN, JSE:ORN) has delivered strong copper grades from infill drilling designed to upgrade the resource of the +105 Level Crown Pillar area at its flagship Prieska Copper-Zinc Project in South Africa.
Fourteen infill holes for a total of 917.87 metres intersected a higher-than-expected mineralised zone, with an additional five holes abandoned due to poor ground conditions and unacceptable core loss.
Shallow results of up to 7.46 metres at 9.24% copper support the company's proposal for early production from the project in Northern Cape Province.
The drilling program is designed to upgrade the existing inferred supergene resource of 630,000 tonnes at 2.2% copper and 1.8% zinc to the indicated category as part of ongoing feasibility studies for the Early Production Strategy.
This supergene resource forms part of the overall resource of 1.76 million tonnes at 1.5% copper and 2.0% zinc for the +105 Level Crown Pillar area.
Significant assays
Assay results from 13 of the 14 holes have returned high-grade copper intersections including:
- 7.46 metres at 9.24% copper, 0.19% zinc, 0.44 g/t gold and 17.46 g/t silver from 45.50 metres;
- 12.53 metres at 4.89% copper, 0.04% zinc, 0.51 g/t gold and 15.12 g/t silver from 43.52 metres;
- 6.05 metres at 5.52% copper, 1.83% zinc, 0.26 g/t gold and 17.18 g/t silver from 45.00 metres;
- 6.25 metres at 1.54% copper, 0.16% zinc, 0.17 g/t gold and 6.62 g/t silver from 62.00 metres;
- 3.10 metres at 2.10% copper, 0.81% zinc, 0.25 g/t gold and 6.76 g/t silver from 51.00 metres; and
- 3.40 metres at 6.91% copper, 0.07% zinc, 0.21 g/t gold and 4.84 g/t silver from 58.00 metres.
The results also show that zinc is depleted in the supergene zone, which the company will re-estimate and re-classify in the updated resource.
An area of geotechnical collapse into underlying mining voids was also confirmed as being confined to a small zone, with less than 10% of the mineralised strike affected.
Final assays for the last intersection are expected shortly.
Section showing the location of the +105 Level Crown Pillar supergene Inferred Resource area.
Mining early start possible
“The infill drilling has confirmed and exceeded our expectations, returning outstanding widths and grades of high-grade copper sulphide mineralisation within the +105 Level Crown Pillar. This is a great result for our team,” said Orion’s managing director and CEO Errol Smart.
“At face value, the grades intersected to date mostly exceed that of the average grade of the standing inferred resource estimate, making the early start of mining via an open pit an increasingly attractive opportunity.
“Our Early Production Strategy aims to target the open pit and remnant pillars while dewatering is undertaken on Prieska Deeps.
"These results provide strong support for that strategy, with the higher-than-expected grades also opening up the possibility that we may be able to undertake shallow underground mining in the early phases of the development, further optimising financial returns.
"Work is continuing as part of the ongoing feasibility studies to determine the optimal approach.”