De Grey reports a major extension of sulphide mineralisation at Hemi prospect

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

The company reported that at the Section B of Hemi prospect, sulphide zone expanded to over 160m wide and greater than 120m depth in RC drilling immediately below the known shallow gold mineralisation.

DEG reported 97m of sulphide mineralisation (downhole) in hole HERC001; and 45m of sulphide mineralisation (downhole) in hole HERC002. The company noted that the new additional parallel sulphide zones increase scale potential with new zones of 19m and 15m (downhole) in HERC002 and HEDD001 precollar.

De Grey said that at Section A of Hemi prospect, intense sulphide mineralization was intersected (up to 20%).

The company said that the mineralisation is now identified as “intrusion hosted” on both Sections A & B. De Grey reported that the aircore drilling has recommenced with further encouraging gold results from previous widespaced program.

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.

RC drilling at Hemi prospect

The company had recently commenced a maiden RC drilling program on Section B of Hemi prospect, followed by drilling on Section A.

DEG said that the ongoing RC drilling program aims to test priority aircore targets with greater detail and depth extensions. The company said that the geological logging and observations of each hole have been undertaken on a 1m basis.

The company reported that two RC holes (HERC001 and HERC002) and a third RC precollar (HEDD001) have been completed on Section B, while maiden RC hole (HERC003) was drilled on Section A. All assay results remain pending for all new RC drilling.

Strong sulphide alteration on Section A and B

De Grey reported that strong sulphide alteration was observed in the RC drilling on both Sections A & B.

Section B

The company said that extensive sulphide mineralisation was observed immediately below the known gold mineralisation and in new parallel sulphide zones to the south on section, which increase the potential to +160m wide to 120m below surface. The sulphide zones and potential remain open in all directions.

Highlights include 97m of sulphide mineralisation (downhole) in HERC001; and 45m of sulphide mineralisation (downhole) in HERC002. The company said that new additional parallel sulphide zones increase scale potential with new zones of 19m and 15m (downhole) in HERC002 and HEDD001 precollar.

The company noted that the alteration assemblage at Section B comprises quartz-sericite-sulphides (pyrite and arsenopyrite) with the sulphides hosted in fine sheeted veins ranging from approximately 5% to 10% of the rock mass.

The fine-grained nature of the sulphide mineralisation makes accurate percentage estimates difficult and full assays results and detailed diamond core are expected to provide further definition of alteration and sulphide percentages.

DEG said that further drilling is currently planned to include an initial diamond core extension to precollar HEDD001 and two planned RC holes to the south prior to step out drilling along strike. All assay results remain pending.

Section A

The company said that the maiden RC hole drilled on Section A targeted a 50m vertical depth extension to the previously reported shallow high grade gold mineralisation of 36m @ 4.0g/t, 49m @ 3.7g/t, 44m @ 5.1g/t, 46m @ 6.6g/t and 24m @ 7.5g/t.

The company said that the hole intersected fresh and intense sulphide mineralisation from 192m (downhole) to 204m where the drilling rods have become bogged and drilling had to cease. A diamond core extension is now planned to complete this hole.

Encouraging AC drill results at Hemi

The company announced that further encouraging gold results have been received from the original 320m x 160m spaced aircore drilling program completed prior to Cyclone Damien.

Significant results include: 45m @ 0.4g/t from 36m including 12m @ 0.9g/t in BWAC357 on Section D.

The company said that additional aircore drilling has recommenced targeting strike extensions of the known mineralisation on 160m x 40-80m spaced holes.

What’s next?

The company said that the programs of follow up RC and diamond drilling aimed at extending resources at depth and laterally are underway or will commence shortly.

De Grey said that further work would also include follow up aircore drilling to test for strike extensions to mineralisation.

Management comments

De Grey’s Technical Director, Andy Beckwith said: “The significant sulphide zones beneath the high grade gold zones on Sections A and B are very encouraging. The large sulphide zones on Section B have the potential to significantly increase Hemi’s scale.

 The genetic link between Sections A and B as intrusion hosted is exciting and increases the potential at Hemi. This is supported by the aircore drilling results to date that highlight every hole above the interpreted intrusions are anomalous in gold.

The aircore and RC programs are continuing, and a diamond rig is expected on site later this week.”

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.