WA – E69/4432 Balladonia – untested gravity core beneath a barren-topped, magnetite-bearing intrusion
Updated: Sep 14
Balladonia is a nickel–copper–PGE, copper–gold and rare-earth target on the buried south-eastern margin of the Albany–Fraser Orogen — the orogen that hosts Nova–Bollinger — under some of the thinnest Eucla Basin cover anywhere on the belt's eastern run: about 37 m. The target has already been drilled, once. In 2011 Enterprise Metals put a single EIS co-funded hole (BLRCD007) into the centre of a ~2,300 m circular magnetic anomaly that is coincident with a ~9 mGal residual Bouguer gravity high — a discrete, first-order geophysical feature by any standard. The hole cored a fresh, magnetite-bearing monzodiorite, the top 54 m assayed barren for gold, and the licence was in time surrendered.
But the diamond tail — the freshest, most magnetic 24.6 m of rock in the entire program, from 54 m to end-of-hole at 78.6 m — was never assayed for anything. And the drilled monzodiorite is not dense enough to explain the gravity anomaly it was collared on. The geophysical question the hole was drilled to answer is still open, and the rock that would answer it is sitting, unanalysed, in the State core library.
This is a re-read opportunity, not a defined-resource one: there is no intercept to headline, because the critical interval has no assays at all — that absence is the opportunity. What makes it attractive is that the whole question can be answered cheaply and decisively before any new drilling. The hole was co-funded, so every record — the logs, the petrography, the airborne magnetics, the raw gravity data — is open file, and the core is preserved and has already been hyperspectrally logged by the Geological Survey of WA, which clears the procedural gate for sampling it. The first step is not a drill rig; it is re-assaying the retained core and re-modelling the existing gravity for a few tens of thousands of dollars, to confirm or kill the interpretation.
The miss, precisely
Enterprise drilled Balladonia once, cleanly, and stopped 24.6 m into exactly the rock the anomaly demanded. The RC pre-collar (0–54 m) was assayed and returned barren gold fire assays with an unusual chemistry — phosphorus running at 2,289–4,696 ppm with elevated light rare earths and niobium, a signature the program had no reason to pursue. At 54 m the hole converted to diamond core, entered fresh, magnetite-bearing monzodiorite, and drilled 24.6 m of it to end-of-hole. That tail was logged, photographed and petrographically described — and not one metre of it was ever sent to a laboratory. The gravity modelling compounds the miss: the drilled intrusion's density cannot account for the ~9 mGal residual high, which means the dense body the survey defined lies deeper, or laterally offset, and was never reached. The program tested the top of the anomaly's magnetic expression and stopped before its gravity cause. The target was not exhausted. It was clipped, and abandoned.
The Counter Argument
The sceptic's case is straightforward. The gravity residual may need no exotic explanation: it rests on just four survey lines, and a thicker root of the same barren monzodiorite could account for much of it. The barren top is evidence, not an accident — 54 m of assays returned nothing, and the GSWA hyperspectral logging shows the tail is fresh but unaltered: no trace of the hydrothermal system a copper–gold argument would want. The phosphorus–REE–niobium numbers are elevated, not extraordinary, and the absence of carbonate weakens any carbonatite reading. Racecourse is a single, unverified result — 20 ppm uranium is far below ore, 185 ppb palladium is an anomaly, not a grade. The simplest reading of the file is a barren intrusion with an over-interpreted residual — and that reading might be right.
Is the Juice Worth the Squeeze?
Yes — because every sentence of the counter argument is testable with rock that already exists, for the price of a laboratory invoice. Core petrophysics and a re-inversion settle the gravity question; one lab batch on the never-assayed 24.6 m settles fertility; re-sampling settles Racecourse. Each kill criterion is explicit, cheap and fast — the whole confirm-or-kill program costs less than one deep drill hole anywhere else in this belt. Against that capped downside sits a first-order, dual-method geophysical target under 37 m of cover in the orogen that produced Nova–Bollinger, where the decisive interval has simply never been analysed. If the answer is no, we will know quickly and completely. If yes, we own the only ground that asked the question.
The Core Image
The thesis in precisely not "there's grade in the core." The ~8 mGal Bouguer high — is the live question, and the only way to answer it is a gravity inversion constrained by measured density and susceptibility from that core. You need physical samples from it regardless of what the assays say.
The HyLogger shows the hole bottoming in more mafic rock (pyroxene <1% → 9%, dark mica 18% in the last metre). A hole that ends going the "right" direction, 40 m into basement, on the strongest gravity anomaly of the program, is the one place a geochemical vector has a chance of showing itself.
Pd 49 ppb at 38–40 m and 45 ppb in BLWB001 are small but ~40× crustal background in a monzodiorite; not a result, but exactly the kind of thing a full PGE suite on the freshest rock either confirms or kills.
XRD on the same pulps settles the silica/K-feldspar discrepancy — which matters because if the rock is quartz-monzodiorite the assumed density drops and the residual gravity argument gets stronger.
Next steps
Staged ~$10–15k screen with the gravity model as the actual decision-maker:
Free first step: request full-resolution tray photography and the native TSG file from GSWA and have Matt look at those rather than the thumbnail. If he says the same thing, fine — expected.
Core viewing at Joe Lord with a handheld susceptibility meter and pXRF, ideally by Matt or a Kalgoorlie-based contractor. That gives you susceptibility, a base-metal/Fe/K/Sr/Nb screen and a first look at the smectite zones and the pyroxene-rich base for a day's cost. If pXRF shows nothing and the rock is as uniform as it looks, you can shrink step 3 further.
Reduced sampling request: not 24.6 m of half-core, but 8–10 discrete samples — the five smectite/fracture zones, the bottom 3 m, and two or three representative intervals — for four-acid multi-element, Pt-Pd-Au fire assay, REE, XRD, plus SG. Roughly a third of the v3.0 Stage 1.4 cost.
Run the gravity/TMI inversion (Stage 1.3) as soon as density and susceptibility are in hand, in parallel with the lab turnaround. If the inversion says the drilled diorite explains the anomaly, the play is over regardless of assays and you relinquish before Y2. If a residual survives, the assay results tell you what kind of body to model.
What the operator's own record says
"All drill core from this project has been submitted to the DMP [Joe Lord] Core Library at Kalgoorlie."
Enterprise Metals Ltd, Eucla Project annual report · WAMEX A90741
The core survives, in the State's custody — and GSWA's HyLogger-3 has since scanned the full 54–79 m tail (2021–2024), confirming fresh, unaltered rock and satisfying the Department's precondition for sampling co-funded core. The geology log records only "rare narrow (<10 cm) very weak silicification" in the tail: no alteration overprint, no complication — a clean, unmodified igneous chemistry waiting to be measured.
The explorers who saw the district's other signal
CRA's downhole gamma logs peaked at up to 500 cps at the tops of carbonaceous beds, which their geologists attributed to "local uranium redox reactions between the reducing coal beds and overlying sediments" — in basal sands they described as "highly pyritic — pyrite acting as cement."
— CRA Exploration, 1982 (WAMEX a36053)
Four decades of workers — Utah Development (1980, roll-front uranium), CRA (1982, lignite), Eucla Mining (1989–91, mineral sands) — independently documented a laterally extensive, reduced, pyritic trap at the base of the Eocene cover across this district. Enterprise's own hole BLRC001 at Racecourse, 9.4 km south of Balladonia, then intersected the trap doing exactly what a trap does: 20.1 ppm uranium with 185 ppb palladium over 77–81 m in carbonaceous basal sediments. No prior worker ever assayed the horizon for palladium; this single intercept remains the only one of its kind in the district, and unexplained. E69/4432's southern arm was drawn specifically to hold it.
Why the ground was walked away from
The program's stated objectives were tested and answered: the near-surface gold assays were barren, the nickel model of the day found no massive sulphide in the top of the intrusion, and exploration moved on. But the surrender judgement rests on 54 m of weathered and transitional rock, assayed for a short commodity list, in a hole that never reached the density anomaly beneath it. The fresh-rock chemistry — the only evidence that could grade the intrusion's fertility for Ni-Cu-PGE, or follow the phosphorus–REE–niobium signal into unweathered rock — was collected and never generated. The magnetic anomaly was explained; the gravity anomaly never was.
Why it was invisible — and still is
Balladonia produces no surface expression: flat, thin Nullarbor cover, no outcrop, no geochemical halo. Its magnetic bullseye has been "explained" in every later compilation by the drilled magnetite diorite — which is true, and beside the point, because magnetite explains the magnetics without explaining the gravity. No electromagnetic survey has ever been flown or walked over the target, and a dense, potentially disseminated or deep source would not have announced itself to any regional dataset since. On the modern open-file record Balladonia reads as "drilled, barren, closed" — unless one checks which metres were actually assayed.
Geological setting
The prospect sits where the Albany–Fraser Orogen's eastern margin runs under the Eucla Basin, ~200 km east of Norseman — a covered continuation of the belt that hosts Nova–Bollinger. At BLRCD007 the cover is only ~37 m of Miocene Nullarbor Limestone over Eocene Werillup Formation sediments, against 100 m+ over most of the belt's eastern extensions: a rare shallow window. The drilled body is a fresh, coarse, magnetite-bearing monzodiorite with orthopyroxene and biotite increasing toward the end of hole — the intrusion is becoming more mafic, not more felsic, with depth. Its elevated phosphorus (apatite-hosted, confirmed by the GSWA hyperspectral logging), light-REE and niobium chemistry permits an alkaline affinity, and the untested ~9 mGal residual leaves room for a denser core or cumulate at depth. Below the cover across the wider licence, the basal Werillup Formation carries the district's reduced pyritic trap — the second, independent, target style.
Exploration history
1980 — Utah Development (a9502). Model: Eucla Basin roll-front uranium. Seven holes ~17–20 km south-east found 10–35 ppm U in vertically weathered basal sands — a real trap, no roll-front, no source beds identified. Departure: off-model.
1982 — CRA Exploration (a36053). Model: Werillup Formation lignite. 40 holes; mapped the formal cover stratigraphy, logged gamma peaks to 500 cps at redox fronts, produced the district depth-to-basement plan, flew the district's only (INPUT) airborne EM at 4 km spacing. Departure: lignite quality.
1989–1991 — Eucla Mining (a28865, a32577, a32578, a34059). Model: heavy-mineral strandlines. 53+ RC holes; the basal "heavy mineral" highs proved to be iron oxides and pyrite — a further expression of the reduced basal trap, not a mineral-sands deposit. Departure: no valuable HM assemblage.
2010–2012 — Enterprise Metals (A90157, A90741). Model: gold and base metals under cover. Airborne magnetics-radiometrics, FUGRO ground gravity, then EIS co-funded drilling including BLRCD007 into the Balladonia anomaly and BLRC001/BLRCD005 at Racecourse. Result: the barren-topped magnetite monzodiorite, the unassayed tail, and the U–Pd intercept. Departure: near-surface assays barren; licence surrendered.
2021–2024 — GSWA (HyLogger-3, Joe Lord Core Library). The State scanned the preserved BLRCD007 tail: fresh, unaltered, apatite-bearing — and, procedurally, now sampleable.
Why the opportunity is still available
Every explorer on this ground was asking a different question — uranium, lignite, mineral sands, then near-surface gold — and each answered its own question correctly. The single hole into the district's best geophysical target was assessed on its weathered top half, for a short commodity list, and the open-file record has read "tested" ever since. Nobody has assayed the fresh rock, and nobody has explained the gravity.
The most significant facts on file
Fact (operator / State records) | Why it matters |
~2,300 m circular magnetic anomaly coincident with a ~9 mGal residual Bouguer high at BLRCD007 | A discrete, dual-method geophysical target — and the gravity component remains unexplained by anything yet drilled. |
BLRCD007: 54–78.6 m of fresh, magnetite-bearing monzodiorite diamond core — zero assays | The only fresh rock ever recovered from the anomaly has no geochemistry. The fertility question is unanswered, not answered in the negative. |
P 2,289–4,696 ppm with elevated LREE and Nb in the assayed pre-collar | An apatite-hosted phosphorus–REE–niobium signature, confirmed mineralogically by GSWA HyLogger data — permissive of an alkaline system nobody followed. |
BLRC001 (Racecourse): 20.1 ppm U with 185 ppb Pd over 77–81 m in carbonaceous basal Werillup Formation | Palladium in a sedimentary redox trap — never explained, never followed up, and no prior worker even assayed for it. |
Core preserved at the Joe Lord Core Library; HyLogged by GSWA 2021–2024; fresh and unaltered | The decisive test needs a sampling request, not a drill rig — and the procedural gate for sampling co-funded core is already met. |
The honest headline: there is no defined resource, no ore-grade intercept, and the central interval has never been assayed — Balladonia is an unfinished-test case, not a grade case. Its strength is a first-order, unexplained gravity anomaly whose only drill hole stopped in barren-topped but never-analysed rock, in a belt whose discovery history is written in exactly this kind of covered geophysical target.
The top two targets
The unexplained gravity core. The drilled monzodiorite cannot produce the ~9 mGal residual. Petrophysics on the retained core, a constrained 3D gravity–magnetic inversion of the existing FUGRO and GSWA datasets, and a first-pass ground EM will locate the dense source — and the 24.6 m of unassayed fresh core will say, for a laboratory invoice, whether the system carries Ni-Cu-PGE tenor or an alkaline P-REE-Nb signature worth chasing into it.
The Racecourse redox trap. The U–Pd intercept in BLRC001 sits in a trap horizon that four independent explorers mapped across the district and none tested for precious metals. Re-sampling retained material and downhole gamma re-logging of the open-file drilling rank this cheaply before any ground disturbance.
The immediate step is deliberately not a drill hole. It is a desktop-and-laboratory program on the existing core and data — re-assaying the tail with the full multi-element, PGE and REE suite the operator never ran, quantitative mineralogy, petrophysics, and an independent re-inversion of the gravity against the now-known geology — designed to confirm or kill the interpretation before any field commitment.
No JORC (2012) Mineral Resource, Ore Reserve or Exploration Target is declared or implied. The exploration results discussed were generated by third parties (Enterprise Metals Ltd, Utah Development Co., CRA Exploration Pty Ltd, Eucla Mining NL) and lodged as GSWA open-file (WAMEX) data; they have been re-read and reinterpreted by CAADIA Metals but have not been verified by re-drilling, re-assay, or a Competent Person for public reporting, and are provided for context only. Values quoted are individual operator sample results and do not represent true widths. The dense-source and redox-trap interpretations are working hypotheses under test; alternative interpretations of the data exist. Exploration Licence E69/4432 was lodged on 4 September 2026 and is an application only — it has not been granted, and objections may be lodged on or before 9 October 2026.
