Larvotto Resouces: Reading a Hillgrove-Style System Through an Antimony Lens: What the Open File Still Holds Over EL6419
Updated: Jul 28
Every so often a piece of ground rewards a second reading — not because the people who hold it have missed anything, but because the questions we ask of a dataset change with the commodity cycle. EL6419 "Hillgrove Regional," held by Hillgrove Mines Pty Ltd and beneficially owned by Larvotto Resources Limited (ASX: LRV), is one of those pieces of ground.
This is a forensic re-read of the in-licence open-file record for EL6419 — the shallow historic drilling and the modern rock-chip campaigns — through an antimony (Sb) and tungsten (W) lens rather than the gold lens under which most of the historic work was collected. It is explicitly not a restatement of the resource and feasibility work Larvotto has already published over the core Hillgrove deposits, which sit outside EL6419 and are referenced here only for geological context.
What makes EL6419 a compelling case study is the quality of the system it sits on. The Hillgrove goldfield is the type example in NSW of a mesozonal, structurally controlled orogenic gold–antimony system — a corridor roughly 8 km by 6 km of dilational, tension-gash fissure lodes in the Girrakool Beds, carrying a gold–antimony–arsenic–(tungsten) association. That is precisely the metal suite the market has re-rated hardest over the last two years, and it is the suite Larvotto's own strategy is built around. The regional licence wraps ground on the same trend, over historic reef workings at Kilcoy, Connindale and Achill, with the Rockvale Monzogranite contact — a natural setting for a tungsten contribution — running right through the Kilcoy prospect.
The core finding of the synthesis is simple and, we think, genuinely encouraging for the current holder: open-file surface sampling defines a coherent, ~700 m antimony corridor at Kilcoy — up to 4.1 % Sb in rock chip — that sits directly above a cluster of shallow 1987 percussion holes for which no downhole assay of any element appears in the public record. The surface signal is real and structurally organised; the near-surface drilling that would test it was collected in an era, and for a commodity, that never required an antimony number. That is not a gap in anyone's current program — it is a gap in the historical record, and it happens to sit inside ground Larvotto already controls. Read that way, the whole exercise is validation: the antimony-gold thesis that underpins Larvotto's flagship also has an untested surface expression on the regional licence around it.
Exploration history
The history relevant to the in-licence ground, reconstructed from the open-file record, runs across five clear eras. Departures are a feature of the commodity cycle and corporate history of each period, not of the ground:
1880s–1920s — Various historic operators. Hand-worked reefs and shallow shafts at Kilcoy, Connindale and Achill. Model: high-grade gold reefs worked to the limit of hand methods and shallow water tables. Objective: gold. They stopped where the easily-worked oxide ore stopped — the universal constraint of the era.
1987 — Aurotech NL (under EL2246). Seventeen shallow reverse-circulation / percussion holes (910 m total, 30–84 m deep) at Connindale and Kilcoy — the only in-licence drilling in the record. Model: shallow gold beneath the historic reefs. Objective: gold. In the open file, every one of these holes is flagged not analysed, not geochemically sampled, not cored. In 1987, with a low gold price and antimony a by-product afterthought, a shallow open-hole percussion program with limited assaying was an entirely rational, budget-appropriate first pass. Aurotech moved on as juniors of that cycle did.
2007 — Straits Resources / Hillgrove. A helicopter-borne magnetic and radiometric survey over the Hillgrove tenements, defining magnetic anomalies (A, C, E) within and around EL6419. Objective: regional structural framework. This was the geophysics era; ground-truthing followed corporate priorities elsewhere.
2013 onward — Bracken Resources → Hillgrove Mines. Tenure consolidation; EL6419 brought under Hillgrove Mines Pty Ltd. The priority of this period was rationalising and holding the package.
2016/17 and 2017/18 — Hillgrove Mines. Two modern, full multi-element rock-chip campaigns — 29 samples (report RE0009831) then 34 samples (report RE0010536), across Kilcoy and Achill. This is the first — and only — modern, laboratory-grade geochemistry in the licence, and it is the backbone of everything that can now be re-read. Credit where due: without these two campaigns, there would be no antimony corridor to point at.
2025 onward — Larvotto Resources Limited. Acquisition of the Hillgrove project and, on 6 May 2025, a Definitive Feasibility Study on the core Hillgrove Antimony–Gold Project. This is the latest and by far the most informed chapter — a well-capitalised operator with a completed DFS, a clear antimony-gold mandate, and the regional licence held around a project it knows better than anyone. The open-file re-read below is offered in that spirit: as a set of options over ground already in the right hands.
Why the grade is still open
Cross-referencing the eras against each other is where the picture sharpens:
The surface geochemistry (2016–2018) says the antimony–gold system is real, spatially organised, and tightly clustered on the western Kilcoy corridor — the pattern of a structurally controlled lode system, not sampling noise. Twelve of 63 rock chips exceed 1,000 ppm Sb; four exceed 1 g/t Au.
The historic drilling (1987) sits physically on top of that corridor — the Kilcoy Dam Lode holes (K7A–K7D) and the Kilcoy 7 & 8 Reef series (K1–K5) — but reached only 30–84 m and carry no open-file assay. So the one dataset that could tell us what the corridor does at depth is, in the public record, silent.
The granite contact (Rockvale Monzogranite, through Kilcoy) keeps the tungsten question open: surface W is weak (max 29.4 ppm), but because no in-licence hole has ever been assayed for tungsten, a deeper scheelite–wolframite contribution is unmeasured, not disproven.
The silver in the high-tenor Kilcoy and Achill samples is very likely under-called: six samples sit at the ME-MS61 100 ppm ceiling, and the 2016/17 narrative cites values to ~956 ppm — meaning the reported silver is a floor, not a grade.
Put together, the system remains under-tested not because anyone declined to test it, but because the surface signal (modern, high-quality) and the near-surface drilling (old, unassayed) have never been joined up with a single Au–Sb–As–W assay suite.
The miss, precisely. The strongest antimony-gold surface anomaly in EL6419 — a ~700 m stibnite corridor running up to 4.1 % Sb with associated gold — sits directly above shallow 1987 percussion holes that were drilled for gold, in a gold-price era, and never carried a publicly recorded downhole assay for antimony, tungsten or anything else. The corridor was walked over, sampled at surface, and drilled through the top 30–80 m — but never once assayed for the metal that now defines its value. The single cheapest, highest-value test of this ground is to recover those historic assays, or re-drill and assay them, for a full Au–Sb–As–W suite.
Significant results
All values below are individual rock-chip (grab) samples from the open-file record — anomalism indicators, not estimates of grade, and not representative of any volume. They are the most significant grades the in-licence system has produced.
Sample | Prospect | Grade | Source report | Operator | Why it matters |
G08363 | Kilcoy (W) | 4.1 % Sb; Ag ≥100 ppm | RE0010536 (2017/18) | Hillgrove Mines | Highest antimony in the licence; anchors the western stibnite corridor |
G08316 | Kilcoy (E) | 3.38 g/t Au; 8,780 ppm As | RE0009831 (2016/17) | Hillgrove Mines | Highest gold in the dataset; defines the eastern arsenic–gold reef |
G08301 | Kilcoy (W) | 2.92 g/t Au; 4,620 ppm Sb | RE0009831 (2016/17) | Hillgrove Mines | Classic gold-plus-antimony pairing sitting over the unassayed holes |
G08366 | Kilcoy (W) | 7,400 ppm Sb; 0.51 g/t Au | RE0010536 (2017/18) | Hillgrove Mines | Second-highest Sb; confirms corridor is not a single-sample spike |
G08302 | Kilcoy (W) | 5,940 ppm Sb; 1.01 g/t Au; Ag ≥100 | RE0009831 (2016/17) | Hillgrove Mines | High Sb + Au + capped Ag together — the full orogenic signature |
G08312 | Kilcoy (E) | 2.79 % As; 0.09 g/t Au | RE0010536 (2017/18) | Hillgrove Mines | Arsenopyrite-rich eastern reef; marks a distinct second structure |
G08340 | Kilcoy (E) | 1.56 % As; Ag 2.23 g/t | RE0010536 (2017/18) | Hillgrove Mines | Confirms lateral extent of the eastern As–Au reef |
G08296 | Achill | Ag ≥100 ppm (to ~956 ppm per report); 575 ppm Sb | RE0009831 (2016/17) | Hillgrove Mines | Best silver in the licence; capped export understates true tenor |
G08290 | Achill | 46.6 g/t Ag; 0.50 g/t Au | RE0009831 (2016/17) | Hillgrove Mines | Uncapped high silver; defines the Achill polymetallic trend |
G08289 | Achill | 9.61 g/t Ag; 0.50 g/t Au; 9.38 ppm Te | RE0009831 (2016/17) | Hillgrove Mines | Ag–Au–Te–Bi signature — a different level in the system |
G08317 | Kilcoy (W) | 3,100 ppm Sb; 0.21 g/t Au | RE0009831 (2016/17) | Hillgrove Mines | Extends the western corridor along strike |
G08314 | Kilcoy | 1.02 g/t Au; 18.55 g/t Ag; 1,920 ppm Sb | RE0009831 (2016/17) | Hillgrove Mines | Multi-metal chip linking the gold and silver systems |
Geological setting
EL6419 lies in the southern New England Orogen, within the late-Palaeozoic accretionary Anaiwan terrane, about 24 km east-south-east of Armidale and immediately north of Waterfall Way. The host is the Girrakool Beds — a Carboniferous turbiditic succession of greywacke, siltstone and slate, deformed to lower greenschist facies and intruded by Hillgrove Suite granitoids. Regional metamorphism and the principal mineralising event are mid-Permian, with late aplite and lamprophyre dykes (dated regionally at ~247–255 Ma) spatially associated with mineralisation.
The mineralisation is the classic Hillgrove orogenic style: narrow, sub-vertical to steeply south-dipping, dilational tension-gash quartz–sulphide lodes carrying gold (with arsenopyrite and pyrite), antimony (as stibnite), and a possible tungsten contribution (scheelite–wolframite) from granitoid thermal aureoles. On the eastern side of the licence the Rockvale Monzogranite intrudes the Girrakool Beds, and its contact passes through the Kilcoy prospect — the specific reason the tungsten question stays open there. The lodes pinch and swell along strike and down dip, with ore shoots rarely exceeding ~100 m in any dimension. That geometry is the single most important control on how the ground must be tested: narrow, steep, discontinuous structures demand tightly spaced, correctly oriented drilling to intersect them cleanly.
Top three targets
Target 1 — Western Kilcoy stibnite corridor (primary). A north–south corridor ~700 m long (roughly 402,170–402,900 mE / 6,630,860–6,631,670 mN, GDA94 / MGA Zone 56), coincident with the historic Kilcoy Dam Lode and Kilcoy 7 & 8 Reef workings. It carries the strongest antimony anomalism in the dataset (to 4.1 % Sb) with associated gold. Testing it — shallow, angled drilling with a full Au–Sb–As–W assay on every interval — would establish down-dip continuity below ~30 m and the gold tenor of the antimony structures at depth. This is the target most directly aligned with Larvotto's stated antimony-gold strategy: it is the same metal association, the same structural style, on the same regional trend as the flagship, expressed at surface over ground already held.
Target 2 — Eastern Kilcoy arsenic–gold reef (secondary). A spatially distinct structure ~2 km east of the stibnite corridor (~404,665–404,874 mE / 6,631,001–6,631,277 mN), hosting the best single gold result in the licence (3.38 g/t Au) in an arsenopyrite-rich reef exposed over ~8 m. Testing would define the strike extent beyond the sampled exposure and provide the first drill test of a gold-dominant structure, complementing the antimony corridor with a gold-led target on the same prospect.
Target 3 — Achill Sb–Ag–As trend (tertiary). A more dispersed polymetallic trend (Ag–As–Sb–Te–Bi) over the Achill workings, with a distinctive silver–tellurium signature that may mark a different level in the mineralising system. The first, near-zero-cost action here is an ore-grade silver re-assay of the capped samples to establish true tenor, followed by structural mapping and, if warranted, drilling. It broadens the regional licence's metal endowment beyond the Kilcoy antimony-gold theme.
Across all three, the recommended sequence in the synthesis is deliberately staged and low-cost, and framed as options for the holder: recover the historic Aurotech assays and confirm the current boundary first (weeks, negligible cost), then tightly spaced surface confirmation, then a small decision-gated shallow RC program. Tungsten is carried in the assay suite throughout at negligible marginal cost — to close the depth question, not because surface tungsten leads the program.
Closing statements
This is not a JORC-compliant statement. Historical results are reported from open-file sources and have not been verified by a Competent Person.
All data are sourced from publicly available NSW DIGS open-file records and public ASX disclosures. CAADIA Metals has no interest in, and no commercial relationship with, Larvotto Resources Limited; the subject tenure (EL6419) is wholly held by Larvotto (through Hillgrove Mines Pty Ltd).
This article is general information only, and is not investment advice or a recommendation regarding Larvotto Resources securities.
Full technical synthesis, intercept overview, drill plan and source register available on request.
