The company considers the latest drilling gold assay results encouraging and sulphide mineralisation has been observed over large widths and depths at the Brolga and Aquila Zones.
De Grey Mining technical director Andy Beckwith said: “Brolga and Aquila are developing into two very large gold systems with widths of gold mineralisation never seen before in the project area nor the Pilbara region.
“The ongoing RC and diamond drilling program aims to scope the overall scale of the mineralisation on 80m spaced sections.
“The large anomalous gold area to the north of Aquila is now our focus for aircore drilling. “Anomalous gold occurs in every hole above the interpreted intrusion in earlier wide spaced aircore drilling and provides scope for further new parallel discoveries.”
RC and diamond drilling has extended Brolga to more than 240 metres strike and 220 metres depth.
Three RC holes (HERC021-023) have been completed on section 30,480E extending sulphide mineralisation a further 80 metres of strike to the west.
This major 80-metre strike extension and the wide zone of sulphide mineralisation logged in the RC drill holes coupled with the gold zones highlighted in the shallow aircore holes of 16 metres at 1.4 g/t, 8 metres at 2.1 g/t and 1 metre at 3.1 g/t, are considered encouraging, particularly as logged sulphide mineralisation has previously correlated well to gold intercepts elsewhere at Hemi.
Around 160 metres to the east of section 30,480E is original section B (30,640E) which delivered RC results of:
- 43 metres at 1.9 g/t from 99 metres, including 6 metres at 4.3 g/t and 4 metres at 5 g/t;
- 36 metres at 3.2 g/t from 156 metres, including 14 metres at 5.6 g/t; and
- 43 metres at 1.9 g/t from 34 metres, including 6 metres at 6.9 g/t.
The previously released intercept 93 metres at 3.3 g/t has been revised to 97 metres at 3.2 g/t, based on additional assays received.
Strong gold mineralisation has also been confirmed along strike on section 30,560E which showed results of 54 metres at 2.2 g/t from 42 metres including 5 metres 6 g/t.
Hemi Prospect drilling plan showing new intercepts and drill hole locations
Aquila is a parallel zone of strong gold and sulphide mineralisation to the immediate north of the Brolga Zone.
RC and aircore drilling has confirmed Aquila’s gold potential over 800 metres strike, up to 50 metres thick high-grade gold zone (greater than 5 g/t on section 30,000E) and 180 metres depth.
RC drilling results include:
- 51 metres at 2.1 g/t from 108 metres, including 8 metres at 4.9 g/t;
- 62 metres at 1.4 g/t from 59 metres; and
- 20 metres at 2.0 g/t from 142 metres, including 3 metres at 6.8g/t.
RC drill results for section 30,400E show lower grade gold mineralisation of 48 metres at 0.4 g/t using a 0.3 g/t cutoff, and a diamond core extension is planned to determine if strong gold mineralisation continues at depth.
Aircore drilling results
The best results from aircore drilling at Aquila are:
- 8 metres at 2.1 g/t from 48 metres;
- 16 metres at 1.4 g/t from 52 metres; and
- 22 metres at 1.5 g/t from 88 metres, including 4 metres at 5.5 g/t.
Aircore drill results in section 30,480E show a broad zone of strong gold mineralisation to the end of the hole of 50 metres at 2.5 g/t - extended from the previously reported 42 metres at 2.7 g/t.
The drilling also showed lower grade gold mineralisation of 16 metres at 0.4 g/t using a 0.3 g/t cutoff.
This variability suggests either depletion and/or variability of gold grade along or vertically with the zone and further detailed drilling will be required to determine the overall gold variability.
Hemi is a new discovery under 30 metres of transported cover, with two zones of strong, broad sulphide rich mineralisation with high grade gold partially defined in the Aquila and Brolga Zones.
The gold mineralisation is associated with strong and extensive sulphide alteration, comprising of pyrite and arsenopyrite, hosted in stockwork within a felsic to mafic phases of the intrusion.
These gold zones represent a major new discovery for De Grey and potentially a new and exciting new style of mineralisation in the Pilbara region.
Hemi has substantial potential to increase De Grey’s current 1.7 million ounces of shallow gold resources.