Northern Molong Porphyry Project background
The NMPP is 100% owned by Alkane, covers c 115km2 of the northern Molong Volcanic Belt and is around 80km to the north-east of its Tomingley Gold Mine, in Central West New South Wales.
The Kaiser geology and mineralisation style is almost identical to Boda and possibly represents a deeper part of the system thrust over the shallower-level Boda deposit. In addition, Alkane’s drill results at Boda-Kaiser have shown a similar stratigraphic sequence and style of alteration and mineralisation to Newmont’s Cadia Province mines 110km to the south. The Cadia complex hosts a mineral resource of 35.2Moz Au at a grade of 0.34g/t Au (including stockpiles and open pit resources – source: Newmont) plus copper, silver and molybdenum, and produced 597koz of gold in Newcrest’s FY23 at an AISC of US$45/oz Au (net of by-product credits) to generate US$1,897m in total revenue and US$1,306m in EBITDA.
The NMPP now comprises five exploration licences: Bodangora, Boda South, Kaiser, Finns Crossing and Comobella (from Sandfire), covering 180km2, within which Alkane has defined five magnetic anomalies interpreted to be intrusive complexes, denoted Kaiser, Boda, Comobella, Driell Creek and Finns Crossing, all within a 15km north-west to south-east trending corridor (Exhibit 7) and all close to road, rail, gas and water infrastructure. Significantly, the Boda anomaly correlates with a historical induced polarisation (IP) survey completed by CRA Exploration (now Rio Tinto) over the Boda Intrusive Complex (BIC). This survey showed a strong, high-chargeable anomaly along the northern edge of the survey area coincident with a magnetic anomaly. As a result, Alkane completed a 70-line kilometre IP survey over the 6km strike extensions of the BIC to generate drilling targets. In late 2023, an airborne gravity survey was also flown over the entire NMPP. Subsequent 3D inversion modelling and interpretation of the data confirmed a 35km2 intrusive complex, termed the Comobella Intrusive Complex (CIC). Peripheral to the CIC, there are also several smaller intrusive complexes, each of which also have the potential to be significantly mineralised. Six of these targets – namely Kaiser, Boda, Comobella, Glen Hollow, Murga and Konigin – have now also been drill tested.
Exhibit 7: Northern Molong Porphyry Project regional geology
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To date, exploration has identified the margins of major monzonite intrusive complexes that provide the primary control for porphyry and epithermal mineralisation, with significant intersections reported along the western margin of both the Kaiser Intrusive Complex and the BIC. Within these, gold mineralisation has been discovered at all six targets (see below), with recent drilling identifying multiple phases of monzonite to monzogabbro intrusion that are plumbing a north-west structural corridor hosting extensive (calc-)potassic alteration and significant gold-copper mineralisation.
Exploration around the Boda-Kaiser area within the NMPP has defined a 3.5km corridor of extensive calc-potassic alteration associated with gold-copper porphyry mineralisation. The corridor trends north from Boda Three to Boda for approximately 1km, where it rotates to the north-west from Boda to Kaiser for a further 2.5km.
Exhibit 8: Boda-Kaiser prospect drilling cross-section
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Within this, the Kaiser porphyry system manifests itself in a series of near-vertical, north-west striking, intrusive related breccias hosted within a thick sequence of andesite lavas. Magmatic-hydrothermal breccias appear to be the focus for the calc-potassic alteration and gold-copper mineralisation at Kaiser, where the highest gold and copper grades are related to the transition from intrusive breccias to hydrothermal breccias. The majority of brecciation is found as ‘crackle breccia’, which can either have a hydrothermal matrix typically composed of calcite + actinolite + pyrite + magnetite + chalcopyrite + bornite or an igneous matrix. Copper mineralisation is also observed throughout the prospect outside the magmatic hydrothermal breccias within calcite + quartz + epidote dominant veins and as disseminations and patches, often intergrown with epidote. Locally, copper has been identified along the Kaiser fault zone in thicknesses up to 10m wide. As shown in Exhibit 6, two significant reverse faults bound and dislocate the main zone of mineralisation at Kaiser, where the west-dipping Solar fault thrusts the Kaiser main zone over the Kaiser east zone. Located immediately north-west of Boda, the east Kaiser zone comprises potassic to inner propylitic alteration with up to 10% pyrite by volume, which can be found to hold gold grades over tens of metres and can average 0.2–0.3g/t in grade with occasional thin intervals of >10g/t Au.
The Boda deposit remains open at depth and along strike to the south and drilling continues to define the overall system, with extensions being tested to the south and at depth at Boda Two and Three, and north-west towards Kaiser. Exploration at Boda Two and Three continues to demonstrate many similarities to Boda, including an extensive zone of low-grade gold-copper porphyry mineralisation with breccias that zone to higher grades. However, it is dislocated by a series of imbricated thrust faults, resulting in deep distal propylitic altered volcanics with minor gold-copper mineralisation in the west being thrust over a central block of broadly calc-potassic altered volcanics with extensive gold-copper mineralisation. These blocks are further thrust over the preserved upper level of the Boda Two and Three porphyry system in the east. Exploration potential remains to target high-grade mineralisation within these blocks (that can be dislocated by up to 500m) and recent drill hole results confirm that mineralisation continues for many metres to the south of Boda and possibly much further. They also demonstrate an extensive zone of low-grade gold-copper porphyry mineralisation with breccias that zone to higher grades. These breccias are in the process of being targeted. For example, at Boda 2–3, the high-grade hydrothermal breccia intersected by drill hole BOD094 was recently tested along strike by two diamond core holes. A chalcopyrite cemented breccia was intersected 40m north and along strike of BOD094 by BOD159 and a more distal hydrothermal breccia was intersected 120m north along strike by BOD158. Results included:
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BOD159 106m grading 0.43g/t AuEq (0.25g/t Au, 0.13% Cu) from 1028m,
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including 5m grading 1.59g/t AuEq (1.09g/t Au, 0.37% Cu) from 1066m,
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and 65.5m grading 1.78g/t AuEq (1.22g/t Au, 0.41% Cu) from 1154.5m,
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including 15.6m grading 6.16g/t AuEq (4.37g/t Au, 1.31% Cu) from 1199.4m,
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including 4.5m grading 11.0g/t AuEq (7.92g/t Au, 2.28% Cu) from 1200.2m,
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and also 2.6m grading 15.1g/t AuEq (10.9g/t Au, 3.06% Cu) from 1211m.
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BOD158 452.6m grading 0.40g/t AuEq (0.21g/t Au, 0.14% Cu) from 852m,
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including 30m grading 0.89g/t AuEq (0.41g/t Au, 0.35% Cu) from 1066m,
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and 8.3m grading 0.81g/t AuEq (0.43g/t Au, 0.28% Cu) from 1413.6m.
At the same time, Alkane is continuing exploration at the Boda Four prospect. Composed of two linear magnetic highs approximately 800m long and up to 200m wide, this prospect is located 1km south and along strike to the BIC and is named the Boda South Intrusive Complex (BSIC). A total of 912m across three RC drill holes have been completed at the northern and central section of the BSIC at the Boda Four prospect, which intersected low-grade copper-gold mineralisation. More recently, assay results were received for one rock chip sample taken from an outcropping hydrothermal epidote-calcite breccia with chalcocite and secondary copper (malachite) mineralisation showing propylitic alteration assemblages very close to the collar of hole BOD134. The sample returned elevated and anomalous grades of:
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RK0000093 grading 1.20% Cu, 12.2g/t Ag and 0.07g/t Au.
Given narrower intersections encountered to date, our estimate of the total mineral inventory at Boda 2-4 is currently 2,779koz, of which we estimate 1,935koz is already included in the existing Boda resource (see Exhibit 9, below). However, if intersections in this area ultimately increase to those implied by the deposit’s apparent 1,100m x 500m coincident gold-copper soil and magnetic high footprint with separate conductive IP anomalies, we calculate that a resource of 9,959koz is possible (ie on a par with the existing Kaiser and Boda resource). In this case, we would value the additional mineralisation at Boda 2-4 at an incremental A$0.476/share to Alkane. As before, readers are cautioned that such estimates are very far from being JORC code-compliant and experience would suggest they have an accuracy of approximately ±80%.
Exhibit 9: Size of Boda Two, Three and Four mineralisation estimates, cf Boda and Kaiser actuals
Source of underlying data |
Edison current estimate |
Alkane |
Actuals |
Characteristic (units) |
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Alkane estimated dimensions |
Kaiser |
Boda |
Kaiser plus Boda |
Strike (m) |
1,144 |
1,100 |
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Average estimated true width (m) |
134 |
500 |
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estimated surface area (m2) |
0.15 |
0.55 |
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Average estimated true depth (m) |
674 |
674 |
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Estimated volume (m3) |
103.4 |
370.6 |
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Estimated density (t/m3) |
3 |
3 |
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Estimated tonnage (Mt) |
310.2 |
1,111.7 |
213 |
583 |
796 |
Estimated average gold grade (g/t) |
0.28 |
0.28 |
0.28 |
0.34 |
0.33 |
Estimated average copper grade (%) |
0.15 |
0.15 |
0.2 |
0.18 |
0.18 |
Estimated average AuE grade (g/t) |
0.48 |
0.48 |
0.55 |
0.58 |
0.58 |
Estimated contained gold (koz) |
2,779 |
9,959 |
1,900 |
6,380 |
8,280 |
Estimated contained copper (kt) |
464 |
1,665 |
420 |
1,030 |
1,460 |
Estimated contained AuE (koz) |
4,745 |
17,004 |
3,740 |
10,872 |
14,700 |
Source: Edison Investment Research, Alkane Resources. Note: Gold equivalent resources and grades calculated at US$2,000/oz Au and US$8,464/t Cu.
Further surface and near surface exploration is planned at Boda 4, including detailed soil sampling and air-core drilling with bottom of hole litho-geochemistry focusing on the west and north-west flanks of the BSIC. In addition, high-definition ground gravity is planned, also extending over the Boda 2–3 and Boda deposits.
Additional regional exploration
Recent regional exploration has targeted the Driell Creek, Konigin and Murga prospects, all positioned within the same (inferred) 15km north-west trending intrusive corridor. Results from nine RC and one diamond core drill holes at Driell Creek, located north-west of Boda-Kaiser, identified porphyry style alteration and mineralisation, including:
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DRC004 130m grading 0.25g/t Au, 0.11% Cu from 174m to end of hole.
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DRC010 47.7m grading 0.12g/t Au, 0.15% Cu from 279.3m,
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including 7m grading 0.34g/t Au, 0.26% Cu from 320m.
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DRC002 9m grading 0.61g/t Au from 255m (gold only zone).
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DRC007 30m grading 0.13g/t Au, 0.10% Cu from 78m,
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and 6m grading 0.26g/t Au, 0.15% Cu from 96m.
Drilling also occurred at the Konigin and Murga prospects. Results indicated that the geology there is favourable for porphyry type environments. However, individual drill results showed weak mineralisation and further drilling at these targets is now considered a lower priority than at Driell Creek. Edison’s summary of the drilling completed to date by Alkane at each of its NMPP prospects illustrates the point:
Exhibit 10: NMPP amalgamated drill hole result summary
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Number of holes |
From (m) |
To (m) |
Average aggregate intercept (m) |
Average gold grade (g/t) |
Average Cu grade (%) |
Boda |
116 |
0.0 |
2,064.4 |
465.6 |
0.28 |
0.13 |
Kaiser |
201 |
0.0 |
1,177.0 |
171.1 |
0.26 |
0.18 |
Glen Hollow |
2 |
42.0 |
267.0 |
45.0 |
0.15 |
0.18 |
Murga |
6 |
129.0 |
195.0 |
3.3 |
0.14 |
0.07 |
Boda 2-3 |
52 |
0.0 |
1,806.8 |
261.3 |
0.28 |
0.15 |
Korridor |
12 |
3.0 |
1,111.0 |
60.2 |
0.28 |
0.10 |
Comobella |
1 |
336.0 |
342.0 |
6.0 |
0.00 |
0.22 |
Konigin |
2 |
153.0 |
652.0 |
10.9 |
0.16 |
0.05 |
Boda 4 |
2 |
15.0 |
234.0 |
6.0 |
0.04 |
0.15 |
Driell Creek |
10 |
54.0 |
335.0 |
21.1 |
0.23 |
0.09 |
Source: Edison Investment Research (underlying data: Alkane Resources). Note: Multiple intersections amalgamated and grades averaged according to the width of the individual intersections.
With the exception of Boda 2–4, given the apparent thinning of the mineralisation (sometimes also at lower grades), we believe that the potential resources contained within Alkane’s other regional prospects – as implied by its drilling results – is, at the moment, fairly negligible. However, given the paucity of drill data, this could change substantially on the basis of even a single new drill hole and we will keep Alkane’s drilling results under review in this respect.
In the meantime, planned regional exploration in the NMPP for the next 12 months will focus on further drill testing of Driell Creek. Other exploration will comprise target generation work composed of mapping, soil sampling, IP, ground gravity and air-core drilling using bottom-of-hole litho-geochemistry, focusing on the Haddington, Windora, Ballimore, Comobella North and Boda 4 prospects and forming part of Alkane’s c A$6m exploration budget for FY25.