Cobar Basin / Lachlan Fold Belt Projects (NSW)
- Metal-rich Cobar Basin / Central Lachlan Fold Belt
- Hera-style high grade gold and base metal targets at Overflow Project
- Porphyry Cu-Au, VMS and Structurallly controlled gold and base metals at Yellow Mountain Project
Alchemy have earned a 51% interest, and can earn up to an 80% interest via a Farm-in Agreement with Heron Resources Ltd (ASX: HRR) in gold and base metal projects covering 674 sq.km in the highly prospective, under explored, central Lachlan Fold Belt (LFB) in NSW.
The LFB projects consist of the Overflow gold and base metal Project (within the Cobar Basin) including drill-ready targets at the historic Overflow mine, the Yellow Mountain gold and base metal Project, the Eurow copper-gold Project, the Girilambone Copper Project and the West Lynn Nickel-Cobalt-Aluminium Project, each containing multiple gold and/or base metal targets. The projects are proximal to high profile mining centres in the Cobar Basin and central LFB, including Hera/Nymagee (Aurelia Metals Ltd), Mallee Bull (Peel Mining Ltd), Tritton (Aeris Resources Ltd), Mineral Hill (Mineral Hill PL) and the North Parkes mining centre (Figure 1).
Figure 1: Alchemy projects, major mines, Au / Cu mineral occurrences, and major structures over aeromagnetic image
Overflow Gold-Base Metal Project (285sq.km)
The Overflow Gold-Base Metal Project consists of four exploration licences located over a 50km long section of the Gilmore Suture at the intersection of the Lachlan Transverse Fault Zone within the well-endowed Cobar Basin (Figure 1). The project is highly prospective for epithermal, porphyry Cu-Au, and Cobar-style Au and base-metal mineralisation.
Mineralisation at the Overflow Prospect is structurally-controlled high-grade Au-Ag and base metal credits, with extensive down-plunge potential, typical of Cobar-style mineralisation (Figure 2).
Figure 2: Schematic Cobar regional long section showing CSA, Nymagee, Hera and Overflow mineralisation
(Source image adapted from Aurelia Mining website)
A review of the historic drilling and 3D modelling of mineralisation at Overflow suggests the mineralisation dips steeply to the WSW, plunges to the south, is associated with distal chlorite-sericite and proximal silica alteration, and displays a significant metal zonation very similar to what is seen at the Hera deposit 30km along strike to the NW.
Metal distributions were modelled for AuEq, Au, Ag, Cu, Zn, and Pb. >1g/t Au grade shell is shown in long section below (Figure 3) and suggests that high-grade Au-Ag and Zn-Pb mineralisation remains open down plunge (Figure 3).
An initial targeted drilling program has been planned to confirm the continuity of high grade gold-silver & lead-zinc mineralisation at depth, down plunge to the south. The southerly plunging grade shells and planned drilling is illustrated in Figure 3.
Drilling by Alchemy in 2017 returned an intercept of 18m @ 2.1g/t Au, 111g/t Ag, 1.1% Zn, 0.3% Pb from 245m. Significant drill intercepts in historic drilling by Delta Gold Limited and Triako Resources Limited at Overflow includes:
| BOBRCPC6 | 4.65m at 8.5g/t Au, 79g/t Ag, 0.22% Cu, 13.5% Zn, 7.1% Pb from 185.4m | |
| TBB001 | 10m at 4.4g/t Au, 21g/t Ag, 0.07% Cu, 3.0% Zn, 1.3% Pb from 163m | |
| TBB006 | 16m at 1.1g/t Au, 88g/t Ag, 0.09% Cu, 1.15% Zn, 0.43% Pb from 162m | |
| TBB008 | 7m at 1.7g/t Au, 135g/t Ag, 0.04% Cu, 1.3% Zn, 0.5% Pb from 198m & | |
| 7m at 6.7g/t Au, 19g/t Ag, 0.32% Cu, 1.9% Zn, 1.4% Pb from 236m | ||
| TBB017 | 6m at 4.7g/t Au, 39g/t Ag, 0.21% Cu, 2.4% Zn, 1.9% Pb from 121m & | |
| 6m at 7.6g/t Au, 29g/t Ag, 0.11% Cu, 3.6% Zn, 1.5% Pb from 136m |
Figure 3: Overflow Prospect Long Section Looking East
Outside of the Overflow Mine area a number of regional targets have been delineated by multi-element anomalism identified in soil sampling analysis (Figure 4). Further exploration and drill testing of these targets is warranted.
Shallow historic percussion drilling at Coopers Hill returned 30m @0.47% Pb from 30m including 6m @ 1.1% Pb (BOB-P03B). At the Parkvale target (Figure 4), narrow high-grade intersections, including 0.7m at 6.8% Cu and 1.2% Pb from 149.4m (BO-1A) drilled in 1977, have not been followed up. Coherent Au-Zn in soil anomalism over an area of 600 x 400m at Prettyview (Figure 5) has not been drilled tested. At the Airport Prospect, outcropping gossans and limited shallow drilling has returned base metal anomalism within semi-coincident EM anomalies.
Figure 4: Historic drilling over Delta Gold Exploration PL 1993-95 soil sampling images (Au, Cu, Pb, Zn).
Yellow Mountain Gold-Base Metal Project (93sq.km)
The Yellow Mountain exploration licence (EL8356) is approximately 25km along strike to the south of Overflow (Figure 1). The licence contains the Yellow Mountain Mine and Melrose prospects; two high priority drill targets both located on splays off the Gilmour Suture, a crustal scale structure associated with several gold deposits in the district, including the Cowal gold mine (current resources 8.6Moz), located 130km south of Yellow Mountain and owned by Evolution Mining (ASX: EVN).
The Yellow Mountain Mine Prospect was last drilled in 1986 with many of the drill holes not assayed for gold. Recent open file data research has identified a poorly tested strong conductivity high centered over the depth extensions of the Yellow Mountain Mine copper-gold mineralisation. The prospect represents a high priority drill target for VMS and structurally controlled copper-gold-silver mineralisation (Figure 5).
Previous drilling at the Yellow Mountain Mine returned a number of broad Cu-Ag-Au intercepts including:
- 52m @ 0.54g/t Au, 0.31% Cu, 35g/t Ag, 1.15% Pb, 1.28% Zn from 14m
- 40m @ 0.49g/t Au, 0.34% Cu, 29g/t Ag, 1.18% Pb, 1.81% Zn from 64m
- 41m @ 0.35g/t Au, 0.23% Cu, 17g/t Ag, 0.85% Pb, 0.94% Zn from 10m
- 78m @ 0.32g/t Au, 25g/t Ag from 57.4m (YD02)
- 66m @ 0.31% Cu, 0.79% Pb, 1.69% Zn from 97.5m (YD02)
- 37m @ 0.28g/t Au, 21g/t Ag from 43.2m (YD05)
- 45m @ 0.24% Cu, 0.58% Pb, 1.07% Zn from 39.6m (YD05)
- 16.5m @ 1.08g/t Au, 0.48% Cu, 52g/t Ag, 2.04% Pb, 3.48% Zn from 198m
- 24.4m @ 1.12% Cu, 1.19% Pb, 1.02% Zn from surface (YP05A) (no Au or Ag assays)
The Yellow Mountain Mine prospect contains strong silica-sericite-pyrite alteration associated with gold-copper-lead-zinc-silver mineralisation within fine grained clastic sediments and siltstones, located stratigraphically beneath a highly resistive dacitic volcanic unit. Mineralisation at the prospect is interpreted to be an exhalative, stratabound VMS system with a structurally controlled Cu-Au mineralisation overprint associated with quartz veins in high strain zones. 3D analysis of the historic drilling results and the IP data suggest the conductivity high could represent the down plunge component of a NE-plunging ore shoot (Figure 5).
(ref. Alchemy Resources ASX announcement dated 9 June 2020)
Figure 5: Yellow Mountain Mine prospect IP conductivity plan (300m RL) (left), and IP conductivity cross section (6408200N) (right).
Melrose Magnetic High – Potential Porphyry Cu-Au System
- 12km long hydrothermal magnetite alteration (Figure 6), geochemically similar to porphyry Cu-Au systems (incl. Cadia-Ridgeway)
- Age dating on alteration zone returned 424Ma – similar to intrusives and sulphides at Mineral Hill (10km to the east)
- Hydrothermally altered & brecciated sediments and volcaniclastic rocks
- No drilling >100m (Figure 6), deeper drilling focused on Fountaindale intrusive ; a potential apophysis off a buried mineralised I-type intrusion
- Large IP Survey planned
Historic drill intercepts from the Fountaindale prospect to the south of the Yellow Mountain mine include:
- 2m @ 3.1g/t Au from 56m
- 2.5m @ 3.1g/t Au, 1.54% As from 70m
- 1m @ 5.5g/t Au from 150m
- 1m @ 4.5g/t Au from 44m
- 3.3m @ 3.1g/t Au from 73m
- 1m @ 5.0g/t Au from 135m
(ref. Alchemy Resources ASX announcement dated 9 June 2020)
Figure 6: : 3D model of the Melrose magnetite alteration anomaly (looking down to the NE) showing the Fountaindale intrusive as a distinct hole in the alteration zone (left), & Melrose (centre) and Cadia-Ridgeway (right) magnetite anomalies at the same scale.
Historic drill intercepts from the Rosedale prospect to the south of the Yellow Mountain mine include:
- 24m @ 2.5g/t Au from 4m (Rosedale)
- 6m @ 3.1g/t Au from 5m (Rosedale)
Figure 7: Yellow Mountain Project – Historic drilling maximum downhole copper over aeromagnetic image (left), and historic drilling maximum downhole gold over geology (right).
Eurow Copper-Gold Project (167sq.km)
The Eurow Copper-Gold Project (“Eurow”), located 30km southeast of Parkes (Figure 1), covers meta-sediments and granite intrusives within the Lachlan Transverse Zone (Figure 8). The Project area contains the historic Eurow-Vychan Cu-Au workings where drilling by previous companies returned high-grade intercepts including:
8m @ 2.95% Cu, 0.85g/t Au from 47m (Eu4)
5m @ 1.83% Cu,1.30g/t Au from 77m (Eu_H)
3m @ 3.99% Cu, 1.25g/t Au from 73m (Eu_D)
2.2m @ 4.65% Cu, 1.78g/t Au from 277.7m (EU027)
3m @ 5.32g/t Au, 0.21% Cu from 11m (Eu1)
3m @ 3.27g/t Au, 4.40% Cu from 89m (Eu_F)
A 3D view of the Eurow Mine drilling looking down to the NNW can be seen in Figure 9. The copper-gold mineralisation dips steeply to the west and appears to plunge to the south. Mineralisation remains open along strike to the north, south, down dip and down plunge. Further drill testing at this prospect is required.
Figure 8: Eurow Project licence (EL8192) over geology.
Figure 9: Eurow historic drilling – 3D view looking down to the NNW. Drill traces coloured by Cu (left) and Au (right).
Girilambone Copper Project (129sq.km)
The Girilambone Copper Project (“Girilambone”) is located 20km east of Aeris’ Tritton copper operation and along strike of the Murrawombie / Girilambone Copper Mine (Figure 1). The area is prospective for ‘Besshi-type’ volcanic massive sulfide (VMS) copper-gold mineralisation within mafic units of the Ordovician Girilambone Group. An historic exploration data compilation and evaluation is underway.