In the previous article, Is Your Data Resource-Ready?, I raised a practical question:

Can a project spend months or years doing good exploration work, find genuine mineralisation, and still reach Mineral Resource estimation stage without all of the information needed to support the Resource it expected to declare?

"Resource-ready" is not a defined JORC term. I use it as a practical description of whether the information supporting an estimate has sufficient integrity, verification, geological support, spatial control, representativity and documentation for a Competent Person to make a defensible assessment.

The original article was largely based on professional experience.

So, what does the published evidence say?

There is no credible global statistic showing that a particular percentage of exploration projects are "not resource-ready". That claim would go beyond the evidence.

What we do have, however, is a useful body of Australian and Canadian research and regulatory reviews showing that gaps in geological confidence, data verification, reporting and Reasonable Prospects can remain visible surprisingly late in the Mineral Resource process.

And occasionally, work already completed has to be redone.

A "warning" down-unda appeared nearly a decade ago

Sterk and Coombes (2017) examined Australian public reporting under the JORC Code, including 25 Mineral Resource reports.

Five of those 25 reports, 20%, lacked an explicit statement on reasonable prospects for eventual economic extraction. The authors were assessing the quality of public reporting, not declaring that 20% of the underlying Resources were technically invalid. That distinction is important.

Their broader concern was that poor reporting can become normalised when practitioners begin treating previous reports as precedent. Sterk and Coombes referred to this as a "lowering-standards effect" (Sterk & Coombes, 2017).

Repeated practice, in other words, does not necessarily make something good practice.

More recent JORC research found a confidence problem

McManus, Rahman, Coombes and Horta (2021) subsequently examined Australian reporting from a different angle.

They randomly selected 180 Mineral Resource and Reserve reports released to the ASX between December 2018 and November 2019. Of these, 142 contained sufficient information for their analysis of geological interpretation and Mineral Estimation Envelope uncertainty.

The findings are particularly relevant to the idea of resource readiness.

Twenty-seven per cent of the reports did not address the quality or confidence of the geological interpretation.

Among the reports that did, the authors identified 19 different qualitative terms being used to describe confidence.

Most strikingly, none of the 142 reports used a quantitative assessment of uncertainty in the geological model.

Only 18% contained at least one quantitative measure of uncertainty, confidence or measurement error anywhere in the criteria examined, most commonly the stated accuracy of GPS equipment used for coordinates (McManus et al., 2021).

That last finding deserves some thought.

A coordinate in a database is not simply a coordinate. The method used to collect it, the expected positional uncertainty and the controls around that measurement affect the confidence it can carry.

The same principle applies more broadly to surveys, density, logging, recovery information and other observations entering the estimate.

A value in the database is not automatically the same thing as a controlled observation.

McManus et al. (2021) also found that only 43% of reports addressed the possibility of alternative geological models. Their later conference paper argued that weak communication of geological uncertainty has implications beyond resource geology because mine planning and financial modelling may effectively inherit a single deterministic geological interpretation without an explicit measure of its uncertainty (McManus et al., 2022).

That is where uncertainty begins travelling beyond the technical model.

Then there is evidence of actual rework

The Canadian Securities Administrators provide perhaps the clearest quantitative example of what can happen when an MRE receives detailed regulatory scrutiny.

In 2020, the CSA published the results of a review of 86 technical reports supporting initial or updated Mineral Resource Estimates.

• Ten of the 86 reports, 12%, were amended and refiled.
• Six required additional disclosure supporting the MRE.
• More significantly, four required the Mineral Resource Estimate itself to be revised because of professional-practice issues.

Those four outcomes comprised a Resource-category downgrade, a reduction in estimated tonnage or grade, a complete recalculation involving verification of historical data, and one retraction of the MRE (Canadian Securities Administrators [CSA], 2020).

That is not evidence that 12% of mining projects fail.

It is not a global MRE error rate.

It is a defined Canadian regulatory-review sample.

But it does demonstrate something much narrower and more defensible:

Mineral Resource work can reach formal reporting and still require material rework.

Interestingly, the estimation process was not always the problem

The same CSA review found that geological modelling, statistical analysis, interpolation and block-model validation were generally among the better-disclosed areas.

Some of the weaker areas sat around the information and assumptions supporting the estimate.

• More than 20% of reports had incomplete disclosure of metallurgical recovery, costs or other factors potentially limiting Resource economics.
• More than 35% inadequately disclosed sensitivity to cut-off grade.
• More than 40% had incomplete disclosure of project-specific factors that could materially affect the MRE (CSA, 2020).

The regulators also noted that many reports lacked sufficient detail around the constraining surfaces used to demonstrate Reasonable Prospects, including pit shells for open-pit deposits and mineable shapes for underground deposits (CSA, 2020).

That goes directly to the distinction between mineralisation and a Mineral Resource.

The geological model may contain the blocks.

That does not automatically mean all those blocks belong in the Resource.

The Australian reporting framework is moving in the same direction

As part of the current JORC Code review, JORC stated that stakeholder feedback indicated that the quality and quantity of discussion around Reasonable Prospects in Public Reports has been variable. One of the stated objectives of the proposed changes is therefore to improve consistency and disclosure around the basis for Reasonable Prospects and the consideration of Modifying Factors (Joint Ore Reserves Committee [JORC], 2024).

That is significant.

It does not retrospectively prove earlier Resources were wrong.

It does show that, years after Sterk and Coombes raised concerns about reasonable-prospects disclosure, the same general area remains sufficiently important to feature prominently in the Code review.

As at August 2026, the JORC Code 2012 remains the operative Code. The provisional replacement is still progressing through final review and approval processes (JORC, 2026).

And the geology still matters

There is another strand to this.

Reid and Cowan (2023) argue that Mineral Resource downgrades can be reduced through better structural geological interpretation and more explicit consideration of geological-model uncertainty. Their work reinforces a basic point: sophisticated estimation does not rescue an interpretation that is geologically inappropriate.

Pressacco, Landry and Evans (2024) reach the issue from the estimation side. Drawing on decades of Mineral Resource work, they describe recurring errors across the MRE workflow and note that errors in the estimate affect the later project stages that rely upon it.

That is probably the most important connection.

An early weakness may initially be relatively small:

• a survey that needs checking;
• density coverage that needs extending;
• core that requires additional logging;
• metallurgical sampling that is not sufficiently representative;
• geological interpretation that needs another test; or
• mining assumptions that require a more realistic constraint.

Find it early and it is another piece of technical work. Find it after the Mineral Resource has been estimated, consultants engaged, studies advanced, budgets approved and expectations established, and the same problem has a much larger footprint.

So, what does the evidence actually tell us?

It does not provide a global resource-readiness failure rate. It does not show that every incomplete dataset produces an incorrect Resource. Regulatory statistics cannot be directly compared between different codes.

But the evidence does support three important observations.

First, material deficiencies can survive surprisingly far into the Mineral Resource process.

Second, confidence is built from more than assays and estimation processes. Geological interpretation, data verification, survey confidence, representative physical-property information, mining assumptions, metallurgy and Reasonable Prospects all contribute to what can ultimately be defended.

Third, once downstream work begins relying on the estimate, a technical problem can stop being only a technical problem.

That was the point of the first article.

Perhaps the better follow-up question is therefore not:

"Is the data resource-ready?"

It is:

"At what point in the project do you want to find out that it isn't?"

Because sooner or later, the Mineral Resource process will test the information sitting underneath the model.

Finding the gap while the project still has options is usually very different from finding it after everything else has already been built on top of it.

Beyond the model

The Mineral Resource estimate is rarely the end of the process. It is usually the beginning of the next one.

Studies advance. Capital decisions are made. Boards approve programs. Management communicates expectations. Analysts and investors form views. Strategies are built on the numbers that came out of the model.

When the information underneath the model is sound, that chain of decisions can proceed on a defensible foundation.

When it is not, the problem does not stay technical for long.

A Resource that needs to be revised, because collars required resurveying, density coverage was inadequate, geological interpretation needed to be reconsidered, or the realistic mining constraint captured substantially less material than expected, does not simply affect the estimate. It affects everything that was already built on top of it.

Studies may need to be revisited. Schedules move. Consultants repeat work. Capital allocation decisions that were made on the basis of the original number may need to be reconsidered. Disclosure obligations arise. The conversation with the board, management and the market becomes more difficult.

That is what the evidence is ultimately pointing at.

Not that Mineral Resource work is routinely wrong. Most of it is done carefully, by experienced professionals, under a rigorous reporting framework.

But the research and regulatory reviews suggest that gaps in confidence, verification and Reasonable Prospects can survive further into the process than they should, and that when they surface late, the cost is rarely confined to the technical work alone.

The judgement behind the number matters. So does the information the number was built on.

That is the connection between resource readiness and everything that happens beyond the model.

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Note: "Resource-ready" is used as a practical professional description and is not a defined term under the JORC Code or NI 43-101. The views expressed in this article are the author's own. References have been cited and applied to the context as accurately as possible.

Canadian Securities Administrators. (2020, June 4). CSA Staff Notice 43-311: Review of mineral resource estimates in technical reports. Canadian Securities Administrators.

Joint Ore Reserves Committee. (2012). Australasian Code for Reporting of Exploration Results, Mineral Resources and Ore Reserves: The JORC Code, 2012 edition. The Australasian Institute of Mining and Metallurgy, Australian Institute of Geoscientists, & Minerals Council of Australia.

Joint Ore Reserves Committee. (2024). Draft JORC Code: Summary of proposed changes. Australasian Joint Ore Reserves Committee.

McManus, S., Rahman, A., Coombes, J., & Horta, A. (2021). Uncertainty assessment of spatial domain models in early stage mining projects: A review. Ore Geology Reviews, 133, 104098.

McManus, S., Rahman, A., Coombes, J., & Horta, A. (2022). Measuring spatial domain models' uncertainty for mining industries. In 12th International Mining Geology Conference: Conference Proceedings (pp. 114–120). The Australasian Institute of Mining and Metallurgy.

Pressacco, R., Landry, P., & Evans, L. (2024). Some common flaws encountered in mineral resource estimation and how to avoid them. CIM Journal, 15(3), 172–200.

Reid, R. J., & Cowan, E. J. (2023). Towards quantifying uncertainties in geological models for mineral resource estimation through outside-in deposit-scale structural geological analysis. Australian Journal of Earth Sciences, 70(7), 990–1009.

Sterk, R., & Coombes, J. (2017). Public reporting — new standards or no standards? In Proceedings of the Tenth International Mining Geology Conference 2017 (pp. 423–432). The Australasian Institute of Mining and Metallurgy.

The JORC Code 2012 Edition remains the operative Code at the time of writing. The provisional replacement is still progressing through final review and approval processes (JORC, 2026).