Mt Edith

Geological setting and mineral system

Mt Edith is a low-sulphidation epithermal Au–Ag–Sb system in the Alum Mountain Volcanics at the northern closure of the Myall Syncline, southern New England Orogen — one of three documented epithermal prospects on a 25 km corridor classified in the open-file record as expressions of a single regional hydrothermal system (Nethery & Jenkins 1988, R00005384). Diagnostic boiling-zone mineralogy — adularia + prehnite + bladed-carbonate pseudomorphs + chalcedonic quartz — is logged in outcrop and historic core (Teale Petrology Studies 1997, in R00020031; petrographic identification, with SWIR/XRD verification scheduled). The model's productive horizon, the Muirs Creek Conglomerate / Alum Mountain Rhyolite interface, is projected at 150–400 m TVD beneath the drill cluster — a stratigraphic inference from the Australmin 1988 regional model, not a measurement: block faulting may step the contact by 100+ m, and no historical hole at Mt Edith has reached it. GSNSW's formal SNEO prospectivity framework contains no epithermal model (GS2017/0619, p. 16), so no published government prospectivity layer corroborates — or condemns — the corridor.

The grades — what the system has already demonstrated

Result (GSNSW open-file)	Confirmation status and Phase 1 action
14 m @ 1.26 g/t Au — ME52 (RC, vertical), Alphadale 1997 (R00020031)	Verified verbatim in the R00020031 report summary — the best-confirmed intercept on the prospect. The from-depth (30 m) and internal sub-intervals (1 m @ 3.44 g/t; 2 m @ 2.92 g/t) derive from drill-log and assay-appendix tables and are scheduled for verification against the original assay appendix (Appendix C, item 5).
34 m @ 0.21 g/t Au + 16 g/t Ag from surface — DD88ME1 (diamond), CRA 1989 (R00004674)	Verified against R00004674 Table 1. A higher-grade internal zone (6 m @ 0.43 g/t Au + 41 g/t Ag) is reported in the same table; its from-depth is under re-check (Appendix C, item 4) and is not stated here.
Peak 1.20 g/t Au over 2 m (aircore); 0.5–1.12 g/t Au in the final samples of multiple 1995 holes — Plumridge 1995 (R00001045)	Reported per the operator's logs. Sixteen of 25 holes ended at refusal in silicified rock — several while still in mineralisation — so the disseminated horizon is effectively untested below the oxide zone. Re-tested directly by Phase 1 holes MERC-01 to -04.
3.45 g/t Au over 0.89 m from 31.10 m (R00005385) / 3.48 g/t Au over 0.89 m from 31.20 m (R00005387) — Freeport DDH2, Pioneer 1990 re-sampling; Northern Grid, ~12 km south, off-application ground	Independent re-sampling of a drilled hole at the model's productive interface — but the two primary records are internally inconsistent; R00005387 is arithmetically consistent, R00005385 is not. Reported here as a range with both sources; resolution against the original assay sheets is Appendix C, item 6. Regional model confirmation only — not on Mt Edith ground.
Surface: auger Au to 1.37 ppm over a ~500 m × 200 m horizon (241 holes, R00001045); rock Au to 1.34 g/t and rock Sb to 1,650 ppm (R00004674 §5.2.2); soil Sb to 400 ppm, Hg to 975 ppb (AOG 1981 via R00005384)	District-significant LS-epithermal pathfinder halo, with the volatile elements (Sb, As, Hg) more strongly anomalous than gold. The surface antimony case rests on documented stibnite at the 1950s pits, the 400 ppm soil halo and the 1,650 ppm rock peak.

Exploration history — seven operators, four licences, documented exits (1980–1997)

Every drilling campaign on the Mt Edith ground intersected gold; no documented exit is a geological condemnation of the untested position — and the model-predicted horizon was never drilled
Period	Operator (licence)	Model targeted	Departure reason (source)
1980–82	AOG Minerals (EL 1485)	Epithermal Au; surface geochemistry	PLA 52 withdrawn after Section 46(2) landowner objection (drill sites within 200 m of the residence); relinquished without drilling (R00011066).
1985–87	Freeport McMoRan (EL 2249 — regional, Alum Mountain, ~13 km S)	Hot-springs boiling zone beneath the silica cap (Leach model)	Withdrew from the JV without earning after two deep holes returned only background gold — a documented negative at Alum Mountain, ground excluded from the CAADIA polygon (R00005383).
1988	Australmin Holdings (EL 2249 — regional)	Stacked-cell convection; boiling at the Muirs Creek Conglomerate / Alum Mountain Rhyolite interface	Recommended 1,500 m of inclined diamond drilling on the interface; six companies inspected the data, five declined; the recommendation was never actioned (R00005384).
1988–89	CRA Exploration (EL 3161)	Epithermal Au beneath the Mt Edith silica cap	Surrendered 1989. The Final Report records only that gamma logging did not change the interpretation; CRA's recorded technical conclusion was that no hole drilled a complete section (R00004674 §5.2.5; R00004675).
1989–90	Pioneer Minerals (EL 2249 — regional)	Interface model follow-up; DDH2 core re-logging	Three percussion holes without significant intercepts; the re-logged vein discovery and the soil anomaly 150 m south of DDH2 were never followed up; relinquished October 1990 (R00005385, R00005388).
1993–97	Werrie Gold / Alphadale (EL 4580)	Shallow-dipping disseminated horizon + NE feeders; auger, aircore, then RC	Relinquished 1997: recorded as sub-economic at 1997 gold prices and metallurgically complex, with 12–16 % cyanide-extractable gold (paraphrased per the R00020031 summary); the 1995 rig could not penetrate silicified fresh rock and the programme ended early (R00001045).

Why the grade is still available — in the operators' own words

Wrong commodity, wrong model. Alphadale's 1997 exit is recorded as sub-economic mineralisation at 1997 gold prices, metallurgically complex, with 12–16 % cyanide-extractable gold (paraphrased per the R00020031 summary). Teale petrology identified the gold as locked in arsenopyrite and stibnite — a flowsheet penalty in a 1997 gold-only frame; under an Au–Sb co-product frame it becomes a processing question that has never been asked of Mt Edith material [not yet tested]. CRA's recorded conclusion on its own 1989 drilling was that no hole drilled a complete section because “all were collared within mineralisation”, and that “gold grades may be improving up section” (R00004674 §5.2.5). No operator ever targeted antimony, despite the 1950s Sb pits on the southern grid.

The analytical gap. The Historical Drill Database audit found that antimony has never been assayed in any Mt Edith drill sample; the historic drill suite was aqua-regia partial digest at 1980s–90s detection limits, the modern LS-epithermal pathfinders (Tl, Te, Bi) were rarely run, and modern Au detection is ~100× more sensitive. The independent surface record already carries the signature the drilling never looked for: soil Sb to 400 ppm and Hg to 975 ppb (AOG 1981 via R00005384), rock Sb to 1,650 ppm and rock As to 4,750 ppm (CRA 1989, R00004674 §5.2.2).

The untested target. Australmin's 1988 reinterpretation formally recommended 1,500 m of inclined diamond drilling in 15 holes along the productive interface (R00005384); six companies inspected the data, five declined, and the recommendation was never actioned. At Mt Edith the synthesis's formulations are precise: the productive horizon predicted by the Australmin 1988 regional model has never been drill-tested at Mt Edith; no historic hole has tested the system below approximately 150 m vertical depth; and, per the drill design, the disseminated gold horizon is effectively untested below the oxide zone — and untested entirely in the down-dip direction where the historical operator's own interpretation places the best grade.

The miss, precisely. Every historical hole was vertical, collared inside the oxide zone, and stopped by refusal or design above ~150 m — into a shallow-dipping horizon whose best grade sits down-dip in fresh rock, and above an interface projected at 150–400 m TVD. No hole was ever assayed for antimony, and no hole was ever aimed at the position the operators' own model and own words pointed to. The grade is still available because the test was never run — not because it was run and failed.

System scale and the 2026 price lens

Footprint (dimensions, not tonnes). A 4 km north–south magnetic-low corridor — sigmoidal, fault-bounded, cross-cutting mapped lithology — extends south from the drilled prospect; the historic drilling footprint (~0.5 km) sits at its northern tip, an order of magnitude smaller. The strongest expression of the low sits 1–2 km south of any drilling and has never been geochemically or geophysically tested at modern resolution; testing along the corridor has been sparse and prospectivity along its southern length is untested and unconstrained either way. The mapped disseminated horizon is ~500 m × 200 m in plan; depth tested is nil below ~150 m vertical against an interface projected at 150–400 m TVD.

Model class, honestly stated. The Sb/Au ratio of ~1,000:1 in the AOG 1981 soils is at the high end of the LS-epithermal range and is qualitatively consistent with the upper part of a vertically zoned system, Au precipitated at depth — a property of the model class, not a prediction for the project (Hillgrove and Costerfield are orogenic Au–Sb analogues, not LS-epithermal, and predict no grade-depth gradient here). The conservative reading is equally open on the present data: the same surface signature is consistent with a near-surface volatile halo over a system that is itself low-grade in gold — the Alum Mountain South case. The discriminating test is direct drilling of the predicted horizon.

The 2026 price lens (the synthesis author's commercial argument — context only; no recovery, mining or processing costs applied; not attributed to any historical operator). Antimony joined Australia's Critical Minerals List on 12 December 2023 (US list 2018); Chinese export controls from September 2024 and the US export ban from December 2024 drove prices to a mid-2025 peak of US$59,750/t and a structurally elevated 2–4× pre-2024 range; a broker-supported long-term evaluation assumption is US$15,000–25,000/t (controls reviewed November 2026). The 1997 exit driver — gold locked in arsenopyrite and stibnite — is, under an Au–Sb co-product flotation frame (demonstrated at Costerfield, proposed at Hillgrove), potentially a credit rather than a penalty; that re-evaluation has not been completed on Mt Edith material and is required before any economic claim can be supported [not yet tested].

The targets

Primary — T1, the disseminated horizon down-dip in fresh rock. Its known limitation is stated plainly in the drill design: the 0.12 → 0.68 g/t Au down-dip grade-increase vector rests on effectively two drill positions and one outcrop, and the historical operator itself framed it as one possible interpretation; and no coordinate records exist for any historical collar, so all positioning depends on georeferencing task PD-1, scheduled first. The designed test: MERC-01 (130 m, −60° toward 225°) undercutting ME19/ME35 at 30–80 m below the base of oxidation, and MERC-02 (160 m) a 50 m down-dip step.

Secondary. T2 N–NE footwall feeder structures — cross-structure test MERC-05 (110 m); vein-grade upside. T3 Au–Ag zone junction on section C–D — MERC-06 (110 m). T4 antimony deportment — Sb in every Phase 1 assay at nil incremental cost, plus deportment mineralogy from diamond hole MEDD-01 (150 m NQ2); treated as upside, not base case. T5 SE-extension scout — MERC-07 (100 m). System-scale (Year 2): the boiling-zone interface itself, a 300–450 m inclined NQ hole; its known limitation is the magnetic corridor's ambiguity — alteration footprint or demagnetised basalt under cover — resolved first by ground gravity (200 m stations), auger geochemistry and IP before collar commitment.

Testing the thesis — gates, kill criteria, cost to answer

Phase + cost	Scope	Gate and kill criterion
Year 1 verification + surface — A$253,000–487,000 (committed Tier-1 scope)	Pulp-retention check, NSW Drill Core Library (first physical step; negligible cost); ~250 archived pulps re-assayed, 47-element 4-acid ICP-MS incl. Sb, Tl, Te, Bi (A$15,000–30,000); DGPS collar re-survey; ground gravity, 200 m stations (A$30,000–50,000); auger/soil traverse (A$30,000–60,000); IP (A$40,000–80,000); QEMSCAN petrography (A$15,000–25,000); staged CP audit.	The analytical-gap kill answer costs A$15,000–30,000 and is binary: the pathfinder/Sb signature either persists in the pulps or it does not. The corridor-identity kill answer (alteration vs demagnetised basalt) is gravity + auger + IP at ~A$100,000–190,000; a negative reframes the play to the drilled-prospect and Sb-pits scale, which do not depend on the corridor. If pulps are not retained, Target-1 drilling defers to CP-supervised resampling.
Phase 1 drilling — A$551,000 incl. 15 % contingency (minimum viable RC-only ≈ A$460,000)	950 m RC in eight holes (MERC-01 to -08, 100–160 m, −60°) + 150 m NQ2 diamond (MEDD-01), RC pre-collar; conditional on grant, access and pre-drilling workstream. QAQC: matched CRMs 1:20 blind (incl. ~0.5 g/t Au and Sb-bearing), coarse blanks 1:20, field duplicates 1:20, ~5 % umpire pulps, ±3 SD acceptance.	Gate to Phase 2: at least two intersections of ≥20 m at ≥0.8 g/t Au-equivalent in fresh rock, or a single feeder intersection of ≥4 m at ≥3 g/t Au. Below-threshold outcomes “trigger structured review against the 'What could kill the play' register” before any further expenditure, and the programme is deliberately structured to retain value in T2, T3 and T5 if the down-dip thesis fails.
Year 2 system test — A$250,000–425,000 per hole; Phase 2 contingent A$0.9–1.2M	Single inclined NQ diamond hole, 300–450 m at −55–60°, to the Muirs Creek Conglomerate / Alum Mountain Rhyolite interface, preceded by the Year-1 gravity/auger/IP discriminators. Phase 2, if gated: 2,000–2,500 m of down-dip/strike step-outs and first northern-corridor tests.	The binary kill-or-confirm event for the regional model: intersecting the predicted contact with no associated mineralisation materially weakens the system thesis (synthesis Risk 1); until drilled, the model remains a defensible hypothesis, not a demonstrated fact.

Technical Manager: Dr Tim McConachy FAusIMM (1974), Senior Fellow SEG, former Rio Tinto Chief Geologist.

Data room (under NDA): technical synthesis v4.1, Phase 1 drill programme design, source register and figure set.

Contact: Doug Alcock, Managing Director, CAADIA Metals Pty Ltd — dalcock@caadiametals.com.au

No JORC (2012) Mineral Resource, Ore Reserve or Exploration Target is declared or implied. Historical results are compiled from GSNSW open-file (DIGS) records, have not been verified by a Competent Person for public reporting, and are provided for context only. The IRGS / distal-replacement interpretation is a working hypothesis under test; alternative interpretations of the geophysical data exist. Earn-in terms are indicative and non-binding, subject to contract, due diligence and grant of the Exploration Licence.