De Grey Mining (ASX: DEG) has announced a significant 1.8km long, up to 80m thick, altered intrusion called Falcon located immediately south of Aquila intrusion at its Hemi Gold Discovery in Western Australia.
The company reported that the new altered intrusion was logged in widespaced aircore drilling. DEG said that the intrusion remains open to the south with aircore drilling continuing.
De Grey reported that the gold mineralisation has been defined over 1.5km in aircore drill assays with additional assays from drilling along strike pending.
Significant initial aircore results include 21m @ 3.4g/t Au from 40m and 19m @ 2.1g/t Au from 68m; 12m @ 2.0g/t Au from 93m; 21m @ 1.1g/t Au from 102m; and 29m @ 1.3g/t Au from 56m.
The company said that the follow-up RC and diamond drilling shows consistent gold mineralisation with intense brecciation and alteration over the northern 240m of strike and to 200m depth. De Grey said that the mineralisation remains open beyond the current 1.8km strike and at depth.
Mallina gold project
De Grey’s Mallina Gold Project is located approx. 60km south of Port Hedland in the Mallina Province of Western Australia. The project hosts numerous large deposits, of which significant gold deposits include Withnell, Mallina, and Toweranna. Other prospects include Hemi, Antwerp, and Scooby. Hemi is surrounded by world-class infrastructure within a Tier 1 mining jurisdiction.
Three zones in Hemi
Hemi is a discovery under 30m of transported cover, with two zones of strong, broad sulphide rich alteration with high grade gold mineralisation partially defined in the Aquila and Brolga zones. De Grey had recently defined a third gold in bedrock zone called the Crow zone located immediately adjacent and north of the Aquila zone.
Drilling at Hemi
The Company had recently commenced aircore (AC), reverse circulation (RC), and diamond drilling (DD) at Hemi to test and extend the known mineralisation.
New Falcon discovery
De Grey said that the recent drilling, west of Brolga and south of Aquila, has delineated a highly brecciated and extensively sulphide altered subvertical intrusion. This new intrusion has been named Falcon.
The company said that the Falcon discovery has been intersected for over 1.8km in strike, up to 80m thick, and to 200m below surface. DEG said that the intrusion remains open along strike and at depth.
De Grey said that intense alteration and style of mineralisation observed to date shows strong similarities to the Aquila zone.
High-grade intercepts from AC drilling
The company announced that the aircore drilling has intersected the altered intrusion over 1.8km in a north south orientation.
Significant new results in aircore drilling include 21m @ 3.4g/t Au from 40m and 19m @ 2.1g/t Au from 68m to EOH in BXAC501; 12m @ 2.0g/t Au from 93m to EOH in BXAC502; 21m @ 1.1g/t Au from 102m in BXAC506; and 29m @ 1.3g/t Au from 56m in BXAC546 (using a 0.3g/t lower cutoff).
Previously reported aircore drilling results include 33m @ 1.5g/t Au from 64m in BWAC567 (ending in mineralisation); 30m @ 0.9g/t Au from 46m in BWAC568; 16m @ 3.7g/t Au from 43m in HERC141 (ending in mineralisation); 16m @ 2.1g/t Au from 44m in BWAC783; and 13m @ 1.8g/t Au from 71m in BWAC908.
DEG said that the drilling orientation has been changed to east west to intersect the intrusion perpendicular to the overall strike. Step out aircore drilling is occurring on 160m spaced sections to the south.
The company noted that the intrusion is highly weathered to partially weathered in the shallow aircore drilling and appears to be variably altered and brecciated on most sections. The bedrock is covered by approximately 30-40m of transported material, similar to the Aquila, Brolga, and Crow deposits.
The company said that the RC drilling is currently underway testing the northern most 240m of strike with over 1.5km of strike remaining to be RC drill tested.
DD and RC results
De Grey said that the first phase RC drilling has returned highly encouraging broad gold intercepts with diamond core extensions showing continuation of the extensively altered intrusion at depth to at least 200 metres.
Encouraging results from RC drilling
The company reported high-grade results from the RC drilling.
Significant results to date from RC drilling include 58m @ 2.1g/t Au from 64m in HERC232 (section 7691640N)-visible gold reported 5 August 2020; 11m @ 1.2g/t Au from 199m in HERC231 (section 7691640N); 24m @ 0.8g/t Au from 167m in HERC233D (section 7691720N); and 31m @ 1.3g/t Au from 88m in HERC234 (section 7691800N).
Previously reported significant RC drilling results include 16m @ 3.7g/t Au from 43m including 10m @ 5.4g/t in HERC141 (ends in mineralisation).
The company noted that the visible gold specimens in HERC232 occur within an interval of 9m @ 4.4g/t Au with a peak of 15g/t Au, forming part of the broader intercept of 58m @ 2.1g/t Au.
DEG said that a diamond core extension to HERC233D was drilled to a total depth of 345.3m and showed strong brecciation and intense sulphide rich alteration over a further down hole length of 69.8m from the end of the RC precollar (192.2m) to 262m.
The company said that extensional RC and diamond drilling are underway on 80m spaced sections, initially targeting gold mineralisation to 200m depth. DEG said that deeper drilling will be undertaken as results warrant.
The company announced that follow up aircore drilling will be undertaken to test for strike extensions to mineralisation.
De Grey said that the programs of follow up RC and diamond drilling aimed at extending resources at depth and laterally are underway.
De Grey Managing Director Glenn Jardine said: “The discovery of the Falcon intrusion demonstrates the potential to significantly grow the gold endowment at Hemi as we expand our drilling footprint.
Reinterpretation of the overall geology shows the Aquila intrusion strikes for 1.2km in a southwest orientation and the new Falcon intrusion strikes for over 1.8km in a distinctly north-south orientation.
Aircore drilling is continuing to track the Falcon intrusion to the south. Opportunities to extend Hemi and to identify similar large scale, near surface Hemi-like intrusions in the Greater Hemi area are being actively pursued, with two aircore rigs in operation.”