De Grey Mining Limited (ASX:DEG) has received further strong gold hits from drilling at the Mt Berghaus deposit of its Pilbara Gold Project in WA that are expected to increase overall resources.
The infill drilling has provided further evidence of shallow gold mineralisation which is expected to improve open pit mining shells which are being formulated as part of a pre-feasibility study (PFS).
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Best results from the Main Lode are 26 metres at 3.45 g/t gold from 3 metres, including 3 metres at 24.37 g/t from 3 metres; and 17 metres at 3.25 g/t from 28 metres, including 4 metres at 7.92 g/t from 33 metres.
North Lode best results are 13 metres at 3.49 g/t from 16 metres, including 4 metres at 10.35 g/t from 21 metres; and 11 metres at 4.92 g/t from 22 metres, including 2 metres at 24.07 g/t from 27 metres.
De Grey’s technical director Andy Beckwith said, “Infill drilling at Mt Berghaus has confirmed significant shallow gold mineralisation which we expect will increase overall resources and positively impact open pit mining optimisation studies as we progress the PFS.”
In March, the company began an infill and extensional reverse circulation (RC) drilling program, targeting improved and additional resources at Mt Berghaus, Mallina, Toweranna and Amanda deposits.
Updated resource model expected
The latest results from 76 holes for 5,155 metres at Mt Berghaus will be included in the updated 2018 resource model.
This RC drilling has focused on infilling existing resource areas to improve the geological understanding and continuity of mineralisation to allow for improved modelling and resource categories.
A regional plan showing the 5-kilometre-long Mt Berghaus gold system.
It has also been seeking additional extensions beyond the current resources and 2017 scoping study open pit shells.
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Other strong Main Lode results are:
The North Lode also returned:
Visible gold in core from the Pilbara Gold Project.
These results continue to reinforce shallow and robust drilling intersections along the 1.2-kilometre mineralised trend, which remains open and generally untested along large portions of the 5-kilometre long anomaly.
140,800 ounce Mt Berghaus resource
The Mt Berghaus resource stands at 3.52 million tonnes at 1.2 g/t for 140,800 ounces and the latest drilling results provide further expectation of improved resource categories and resource ounces.
Once a new resource model has been completed, open pit mining optimisations will be undertaken as part of the wider Pilbara Gold - Open Pit Mining Pre-Feasibility Study.
A program of short diamond tails is planned to begin shortly planned to extend existing RC holes to gain further geological information.
Follow-up drilling
This will be used to plan follow-up drilling, which is likely to include targeting shallow lateral extensions and deeper higher grade underground style mineralisation.
De Grey plans to carry out a trial Sub-Audio Magnetic (SAM) geophysical survey over the Mt Berghaus anomaly, targeting greater definition of the gold hosting structures.
Successful definition of the controlling gold structures would allow for targeted RC and/or aircore drill testing in the search for additional shallow resources.
Planning of this survey is underway and is expected to be completed during October, subject to contractor availability.
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The Pilbara Gold Project has excellent potential to define significant additional resource ounces along its 200 kilometre-plus strike length of mineralised shears zones throughout the 1,500 square kilometre land holding.
To date, around 10% of the shear zones have received detailed shallow RC and diamond drilling to a nominal depth of 100-150 metres.
This has already defined mineral resources containing more than 1.2 million ounces of gold.
A resource update is underway and is expected to be reported in late September/early October of 2018.