De Grey confirms large scale gold system at Hemi

De Grey Mining Limited (ASX: DEG) has announced a highly encouraging update on the RC drilling at the Hemi Prospect within its Mallina Gold Project in WA.

The company reported that the latest drill results from Hemi discovery have confirmed a large-scale gold system, with the Brolga Zone returning an RC intersection of 93m @ 3.3g/t Au.

DEG said that at Aquila Zone, a northeast trend has been defined over more than 750 metres of strike and up to 50 metres wide.

Significant results include 11m @ 3.0 g/t Au from 193m finishing in high grade mineralisation of 4m+ @ 6.5g/t Au; 38m @ 3.4 g/t Au from 55m including 9m @ 7.4g/t, 50m to the north east; and 42m+ @ 2.7g/t Au from 96m including 4m @ 4.2g/t Au, 480m along strike to NE and finishes in mineralisation.

The company said that the RC drilling confirmed strong gold mineralisation at depth, potential +320m of strike and up to 200m wide at Brolga Zone (formally, Section B).

Highlights include 93m @ 3.3g/t Au from 39m including 21m @ 4.7g/t Au, confirming broad gold zone at depth that correlates with the shallow aircore gold results directly above; 51m @ 2.2g/t Au from 98m including 8m @ 4.1g/t Au, extending 40m down dip.

De Grey said that the RC and aircore drilling have defined two separate parallel gold zones, Aquila and Brolga; strong gold mineralisation associated with extensive sulphide rich alteration; increased sulphide alteration to over 200m wide at the Brolga Zone; strike length of +750m and up to 50m true width along the Aquila Zone; and potential multiple zones.

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 1.7 Moz Mallina project hosts numerous large deposits. Significant gold deposits include Withnell, Mallina, and Toweranna. Other prospects include Hemi, Antwerp, and Scooby prospect.

Withnell is the largest gold resource at Mallina, currently hosting a combined open pit and underground resource of 4.65 million tonnes at 2.9g/t for 429,300oz of gold.

Hemi prospect comprises of the initial discovery Section A, as well as Section B, Section C, and Section D.

Drilling at Hemi

The company said that since recommencing drilling in January 2020, 13 RC holes (HERC001 – HERC013) and 3 RC precollars (HEDD001 – HEDD003) totaling 2784m and 115 aircore holes (BWAC309 to BWAC423) totaling 10,360m have been completed at Hemi.

De Grey said that full assays remain pending for 15 RC holes (1 complete and 3 partial RC results received) and a further 47 aircore holes.

DEG said that a diamond core rig is on site and has commenced with HEDD001 at the Brolga Zone (Section B). Drilling is targeting along strike and down dip extensions of the sulphide rich alteration zones to outline the potential scale of the deposit prior to infill resource definition drilling.

Assays reported from Hemi

De Grey has now reported on gold assay results from the initial RC and the ongoing aircore drilling programs underway at the newly discovered Hemi Prospect. This includes the initial RC drilling gold assays from the Brolga Zone (Section B) and the Aquila Zone (Section A and extensions), together with additional aircore results.

De Grey said that further assays remain pending on both zones.

The company reported that the ongoing RC and aircore drilling continue to define the sulphide alteration along strike, over increased widths and down dip on generally widespaced sections between 80-160m apart.

Brolga Zone (Section B)

De Grey reported that a total of seven (7) RC holes, including two precollars (HERC001-002, HEDD001-002 and HERC011-013) have now been drilled at the Brolga Zone, with at least two of the holes (HEDD001, HEDD002) planned as precollars for planned diamond extensions to test mineralisation at depth.

The company announced that at the Brolga Zone, the drilling has highlighted the overall sulphide alteration extending to over +200m wide and down to the current depth of drilling at approximately 150m below surface and potentially +320m of strike.

The company reported that highly encouraging gold results have now been received for HERC001 and partially received for HERC002.

Significant results include 93m @ 3.3g/t Au from 39m in HERC001, including 21m @ 4.7g/t Au and 12m @ 1.9/t Au from 140m in HERC001; and 51m @ 2.2g/t Au from 98m in HERC002 (partial results), including 8m @ 4.1g/t Au and 12m @ 1.6g/t Au from 160m in HERC002.

The company said that further RC drilling results across this broad alteration zone remain pending.

The company said that the sulphide zone has been expanded to +200m wide and potential for +320m of strike. DEG reported that the diamond drilling has commenced.

Aquila Zone (Section A)

The company said that the drilling at the newly named Aquila Zone has focused on confirming the strike orientation of the subvertical high grade gold zone previously defined in the earlier aircore drilling.

DEG said that several aircore fences and nine RC holes have now been completed along strike from Section A.

The combined 80m spaced aircore and RC drilling has defined the Aquila Zone over a strike length of at least 750m.

New significant drilling results along the 750m long Aquila Zone include 11m @ 3.0 g/t Au from 193m in HERC003. The hole finishes in high grade mineralisation (4m+@ 6.5g/t Au); 38m @ 3.4 g/t Au from 55m in HERC004 including 9m @ 7.4g/t Au; and 42m+ @ 2.7g/t Au from 96m in BWAC397 including 4m @ 4.2g/t Au (aircore).

DEG said that mineralisation has been confirmed to 180m below surface and remains open.

De Grey said that two RC holes were completed 50m east of Section A (local grid 30050E) to assist in determining strike orientation. Both these holes intersected strong sulphide mineralisation where expected, and hole HERC004 assays have confirmed continuation of the strong gold mineralisation with 38m @ 3.4 g/t Au including 9m @ 7.4g/t in HERC004. All other RC assay results from the Aquila zone are pending.

Aircore holes

The company said that aircore hole BWAC397, 480m along strike to the NE of Section A returned 42m @ 2.7g/t Au in strong sulphide-rich mineralisation, from 96m to the bottom of hole and remains open at depth.

Aircore hole BWAC395, 160m south west of Section A intersected 9m @ 0.6g/t Au in encouraging sulphide alteration, within a broader zone of 41m @ 0.3g/t Au (using a 0.1g/t Au lower cut). Further aircore results along strike remain pending.

Updates and next steps

The company announced that an RC rig and a diamond rig are currently on site following up and extending mineralisation along strike and at depth.

Aircore drilling is also ongoing, assisting with defining mineralised trends for later follow up by RC and diamond drilling.

The company said that the current widespaced drilling program, on nominal 80-160m sections, aims to scope out the scale and trends of the mineralised envelopes within the 2.5km long prospective corridor. Detailed resource definition RC and diamond drilling will then be designed to infill and extend mineralisation on 80m spaced sections to define an initial inferred resource at Hemi.

De Grey said that follow up aircore drilling will be undertaken to test for strike extensions to mineralisation. The company reported that the programs of follow up RC and diamond drilling aimed at extending resources at depth and laterally are underway.

Management comments

De Grey’s Exploration Manager Phil Tornatora said: “Early drilling at Hemi has produced some of the best discovery intersections that I have seen. Drilling to date, shows exceptionally wide, continuous and good grade gold mineralisation.

Geological indications suggest that Hemi may be more of an intrusion related style of gold system rather than the more typical orogenic shear hosted style deposits of the Pilbara and other WA goldfields.

We have three rigs on site advancing this exciting new discovery.”

Written By Jonathan Norris
Jonathan is a founder of and has been covering the resources industry since 2018. With over 17 years experience in print, broadcast and online media, Jonathan has seen first hand the transformative effect of online niche media.