De Grey Mining Limited (ASX:DEG) has intersected bonanza grade gold of up to 58.9 g/t at the Toweranna deposit within the wider Pilbara Gold Project in WA.
These grades were returned from broad intersections in gold zones below and east of the existing resource model that are expected to support material resource extensions at Toweranna.
The best bulk intersection of 136 metres at 2.0 g/t from 94 metres includes 26 metres at 3.07 g/t and 29 metres at 4.38 g/t.
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These results are from the first 12 holes for a total of 2,888 metres of a planned 5,400-metre resource extension drilling program.
The drilling has been completed on a 40 by 40-metre basis targeting lateral and depth extensions to the existing shallow 2018 Toweranna mineral resource of 2.01 million tonnes at 2.2 g/t for 143,900 ounces.
Material extensions "likely"
De Grey Mining technical director Andy Beckwith said: “We are very pleased with these new drill results as they confirm strong gold mineralisation occurs to at least 200 metres below surface and material extensions are likely with further drilling.
“The potential to extend resources from 200 to 400-metre depth will be our next focus.
“The bonanza high-grade nature of some of the individual veins is also particularly encouraging as it suggests selective or bulk underground mining methods may be possible.
“Importantly the new drilling shows Toweranna has multiple stacked lodes across the entire intrusion, strong mineralisation extending at depth and remains.
“This is a new style of mineralisation for the Pilbara and similar style deposits elsewhere around the world validates the potential for large scale and multi-million-ounce resources.”
High-grade results
Results below 100 metres include:
- 29 metres at 4.38 g/t from 201 metres, including 1-metre at 41.9 g/t and 2 metres at 29.9 g/t;
- 26 metres at 3.07 g/t from 94 metres, including 5 metres at 8.36 g/t;
- 6 metres at 6.45 g/t from 135 metres, including 1-metre at 20.3 g/t;
- 6 metres at 3.5 g/t from 204 metres;
- 3 metres at 7.02 g/t from 150 metres; and
- 5 metres at 5.04 g/t from 218 metres, including 1 metre at 22.9 g/t.
Many of the new lodes show individual veins of 1-2 metres width with bonanza gold grades in excess of 20 g/t and include individual intercepts of 1-metre at 58.9 g/t, 1-metre at 20.3, 1-metre at 51.7, 2 metres at 22.15, 1-metre at 22.9, 1-metre at 22.7, 1-metre at 21.4, 1-metre at 41.9 and 2 metres at 29.9.
This bonanza high-grade mineralisation is also demonstrated by historic small scale underground mining along selected shallow lodes that partially outcrop along the western contact where the mine produced 5,000 ounces at gold at an average grade of 40 g/t.
The very high grades provide added support for potential underground mining at depths beyond any open pit mining.
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The existing resource occurs mostly along the western and southern portions of the granitoid plug and is constrained by the limit of drilling down to about 100 metres depth.
New drilling has intersected significant shallow lateral lode extensions and new lodes within the upper 100-metre zone.
The deeper drilling, generally to 250 metres downhole, has continued to extend existing lodes east of the resource model and intersected numerous stacked lodes at depth.
De Grey has planned the next round of reverse circulation drilling to extend and define the lodes down to about 200 metres below surface with diamond drilling planned to test and extend mineralisation to at least 400 metres.