ValidaAuditoria
Note 03 · 24/09/2026
See what is proven and what is assumedUntil August 8, 2022, the mineral exploration reports filed with the Agência Nacional de Mineração (ANM, Brazil's National Mining Agency) spoke of "measured reserve," "indicated reserve" and "inferred reserve." On that day Resolução nº 94/2022 (Resolution 94/2022) took effect, and the three came to be read as resources. A report that announces a "measured reserve of 12 million tonnes" may therefore be written in the earlier vocabulary, or may mix two things that today's rule keeps apart. "Measured" went to the resource, the ore that the research located and that has reasonable prospects of paying off. "Reserve" was kept in reserve, pardon the pun, for the part that a study showed will pay for itself. Anyone reading an old report, or a new report written in the old vocabulary, needs to know which of the two things is being bought.
As Valida reads it, "Measured, Indicated, Inferred" does not say how much ore exists. It says how confidently someone states the quantity. The audit checks whether the method and the signature behind the word support the label, because between "Inferred" and "Measured" the value, the risk and the timeline of any decision about the asset all change.
The starting point is constitutional. The Constitution, in art. 176, separates the ore from the land: deposits "constitute property distinct from that of the soil" and belong to the Union. Decreto 9.406/2018 (Decree 9,406/2018), which regulates the Mining Code, calls a deposit "every individualized mass of mineral substance" that "has economic value." The deposit is the treasure. The deed to the land does not include it.
The treasure reaches paper in layers. The first is the mineral resource. ANM Resolution 94 defines it as a concentration of mineral substance that, once measured, shows a shape, grade and quantity "with reasonable prospects for economic use." Grade is the proportion of useful ore in the rock, such as how much iron there is in each tonne. A resource is a well-drawn treasure map: it says where the ore is, how much there is and how rich it is. It does not yet say whether digging pays.
Not everything that was found becomes a resource. The CBRR guide, from the Comissão Brasileira de Recursos e Reservas (Brazilian Commission on Resources and Reserves), which the resolution itself orders to be followed, translates "reasonable prospects" as economic extraction "tending to be more likely than not," in any category. Rock with ore but without that prospect stays off the map.
The second layer is the mineral reserve: the "economically mineable part" of a Measured or Indicated resource, "whose technical and economic feasibility of mining has been demonstrated" by studies. Mining is the extraction itself. The studies apply the modifying factors, which the resolution lists: mining method, processing, metallurgy, infrastructure, economics, marketing, and legal, environmental, social and governmental aspects. It is everything that separates having the harvest in the field from having the money in the bank: cost, freight, buyer, license. A reserve is the account of what can be taken out at a profit.
Before the two layers there is a step, the exploration target: the mineralized body that has not yet had enough research for a resource to be estimated. The rule only allows it to be expressed "as a range of tonnes and grades." A fixed number at this stage is a clock set ahead.
The change has a date and an address. ANM Resolution 94 is dated February 7, 2022, was published on February 8 and took effect 180 days later. The ANM guide to the 2023 Relatório Anual de Lavra (RAL, Annual Mining Report) sets the start of effect at August 8, 2022. Decree 9,406, in art. 9, §4, ordered that "Inferred, Indicated and Measured resources" and "Probable and Proved reserves" be classified on the basis of "internationally accepted standards."
Until then, Brazilian documents spoke of measured reserve, indicated reserve and inferred reserve. It was like calling both a deposited salary and a promised raise "money in the bank." The ANM replaced the "Mineral Reserves" screen of the annual report with "Mineral Resources and Reserves," and the official news item on the change warns that the changes "do not alter only nomenclature." Art. 9 of the resolution built the bridge to the old papers, with one regime for exploration reports and another for the economic exploitation plan, which accompanies the mining application.
| In a document prior to 08/08/2022 | Read today as | What changes for the decision-maker |
|---|---|---|
| Measured reserve (exploration report) | Measured resource | High confidence in the quantity; feasibility not yet demonstrated |
| Indicated reserve (exploration report) | Indicated resource | Basis for planning; at most, a Probable reserve |
| Inferred reserve | Inferred resource | Informed guess; does not become a reserve |
| Economically mineable portion of the measured reserve (economic exploitation plan) | Proved reserve | Here the word reserve stays standing |
| Economically mineable portion of the indicated reserve (economic exploitation plan) | Probable reserve | Reserve, with lower confidence |
| Non-mineable portion of the measured reserve (economic exploitation plan) | Measured resource | Goes back to being a resource |
| Indicated reserve without demonstrated economics (economic exploitation plan) | Indicated resource | Also goes back to being a resource |
Two practical consequences. An old report with "measured reserve" is not wrong: it is written in another language and needs the table to be read. Art. 10, in turn, orders the new concepts to be applied, mandatorily, to the technical documents of mining processes and to public declarations after the start of effect. The rule does not reach private reports but, as Valida reads it, a new report with the old vocabulary is a sign to investigate, not a detail of style. The title of this note uses the three words the way reports before 2022 wrote them. The rest of it uses today's.
To estimate what lies underground, exploration drills the land and pulls out cylinders of rock for analysis. Decree 9,406 lists this work: "drilling in the mineral body," "systematic sampling," physical and chemical analyses of the "drill cores," which are the cylinders. It works like sticking a toothpick into a cake at several points to learn whether the filling is the same all the way through. Few toothpicks, a guess. Many, well distributed, a reasonable certainty. Nobody eats the whole cake to find out.
ANM Resolution 94 ranks the three resource categories "according to the degree of reliability of the geological research":
The verbs do the work: suggest, assume, confirm. The CRIRSCO international template, from the Committee for Mineral Reserves International Reporting Standards (CRIRSCO), whose standard the resolution orders to be followed, uses the same ladder: "imply but not verify," "assume," "confirm." The Australian code, the JORC, and the rule of the United States securities regulator, S-K 1300, speak the same language, each with its own accent.
| Category | Verb of the rule | Can it become a reserve? |
|---|---|---|
| Inferred | Suggests | No. "Must not be converted to mineral reserve" |
| Indicated | Assumes | Only into a Probable reserve |
| Measured | Confirms | Into a Proved reserve or, "under certain circumstances," a Probable one |
One caveat is worth gold. None of the rules examined fixes the distance between drill holes that turns a resource into "Measured." The CBRR guide says the category depends on "the quantity, distribution and quality of the data" and that classifying resources "is a matter of expert judgment." JORC, in clause 24, says the same: "a matter for skilled judgement." The ruler is not a tape measure. It is a person, which is why the signature weighs as much as the number.
The simplest rule of the system has a direct effect on price: an Inferred resource does not become a reserve. ANM Resolution 94 says it "must not be converted to mineral reserve." CRIRSCO, in clause 7.7, adds that it cannot even be presented as part of the reserve. JORC repeats the prohibition in clause 21. The American rule explains the reason: the geological uncertainty of the Inferred is too high for the economic factors to be applied in a way that is useful for assessing viability.
The Brazilian decree reaches the same point by another path. Art. 9, §6, says that economic viability follows from a preliminary study based on costs, freight, the market and "Measured and Indicated resources." The Inferred is not on the list. Not out of contempt; out of prudence.
There is a legitimate hope in the Inferred, and CRIRSCO records it: it is "reasonably expected" that most of it could be upgraded to Indicated with further exploration. Right after, it warns that this should not be presumed to always happen. That is why, when the resource is predominantly Inferred, the report must give the reader the elements to assess the risk (clause 7.5). And, when the estimate stretches beyond the spacing of the sampling, it must say how far it stretched, what part of the resource comes from that extrapolation and on what basis (clause 7.6). To extrapolate is to extend the line past the last measured point. Useful, as long as it says where the ruler ends and faith begins.
Here lies the most expensive confusion. Lei 13.575/2017 (Law 13,575/2017), which created the ANM, in art. 2, XXXV, speaks of a "Brazilian system for certification of mineral reserves and resources." The word invites you to imagine an official stamp on every number. ANM Resolution 94 dispels the impression in the sole paragraph of art. 2: "The ANM has no mandate as a certifying institution of the exploration results, resources and mineral reserves presented in the public reports by the holders of mineral rights."
A public report is the official summary that the holder publishes: the asset's fact sheet. Submitting it to the ANM is optional (art. 5, §3). When it exists, it must follow the CRIRSCO and CBRR templates (§2) and "be consistent with" the technical documents submitted to the agency (§5).
The agency does not stand idle. Under the Código de Mineração (Mining Code), art. 30, it examines the final exploration report and approves it "when the existence of a deposit has been demonstrated," or rejects it for insufficient work or technical deficiency. Approval, however, does not make the State the guarantor of the number. Decree 9,406, art. 73, puts the truthfulness of the data on the shoulders of the technical manager and the holder, under pain of criminal and administrative liability. The sole paragraph wraps it up: approval of plans and reports gives rise to no "responsibility of the Public Authority" if the data is inaccurate or false. The resolution repeats the division in art. 12, §3, in the civil sphere as well.
The seal the buyer needs, therefore, does not come from Brasília. It comes from the method and from whoever signs it.
ANM Resolution 94 requires, in art. 8, that the declarations be "prepared and signed by a qualified professional." In art. 7, it sets three criteria. Transparency: information that is "sufficient, clear and unambiguous." Materiality: everything that is relevant and, for each relevant item omitted, "a justification for its absence." Competence: work by qualified, experienced professionals "subject to a code of ethics."
The international codes call this person a Competent Person; the Brazilian guide, a Qualified Professional. It is the equivalent of the engineer who signs the structural report: the signature answers for it.
| Reference | Experience required of the signatory | What else is required |
|---|---|---|
| CBRR guide (Brazil) | 10 years in the profession, 5 of relevant experience and 3 in a position of responsibility, for registration with the CBRR | Work not "unduly influenced" by whoever commissioned it; a visit to the property, if accessible. Alternative to registration: membership in a recognized professional organization |
| CRIRSCO (international template) | 5 relevant years in the type of deposit and in the activity performed | Public name, employment relationship, conflict of interest disclosed, written consent |
| JORC (Australia) | 5 years of relevant experience | Name disclosed and any potential conflict of interest |
| S-K 1300 (United States) | 5 relevant years in the type of mineralization and deposit | Membership in a recognized professional organization |
The common denominator is a professional organization with the power to punish. CRIRSCO requires that it be able to suspend or expel the member. As Valida reads it, this is where the word gains weight: a "Measured" label is worth as much as the record of whoever is willing to answer for it. The note on who signs and why deals with the same idea in the audit opinion.
An illustrative situation, built only to show the calculation; it is not a real case, client or official data. A report says on its cover "measured reserve of 12 million tonnes" (Mt). In the annexes, the table by category tells another story: 4 Mt Measured, 5 Mt Indicated, 3 Mt Inferred.
| Step | Result | How we get there |
|---|---|---|
| Total announced on the cover | 12 Mt | 4 + 5 + 3 |
| Part actually measured | 4 Mt, 33% of the total | 4 ÷ 12 |
| Ceiling of what can become a reserve, if there is a feasibility study | 9 Mt, 75% of the total | Measured + Indicated: 4 + 5 |
| Ceiling of Proved reserve | 4 Mt | Only what comes from the Measured |
| Portion that reaches, at most, a Probable reserve | 5 Mt | The Indicated (ANM Resolution 94, art. 4) |
| Inferred, outside any reserve | 3 Mt, 25% of the total | 3 ÷ 12 |
| Distance between the cover and the normative ceiling | 3 Mt, a quarter of the volume | 12 minus 9 |
The report does not need a single wrong number for the cover to be stronger than the method. It added up different categories under the name of the strongest of them and called a reserve something that is still a resource. The CBRR guide forbids declaring the categories in combined form unless the detail of each one is also provided (item 6.15). Here the detail exists, but in the annex, while the cover says something else. If the investor priced 12, the rule supports at most 9 as a reserve base.
There is no grade, price or cost; a tonne is not value. And 9 Mt is a ceiling, not a forecast: a reserve only exists after the study with modifying factors. The calculation measures the distance between the word and the method. How much that distance costs depends on everything else.
As Valida reads it, the verification puts four questions to the report. Does the announced category match the table by category? Do the distribution of drill holes and the justification of continuity support that category? Are the laboratory assays traceable? Who signs, under which code, with what relationship and with what declared conflict of interest? The CBRR guide, in its Table 1, asks for this discussion "to establish the degree of geological continuity and appropriate grade."
When the method supports a category below the one announced, the finding is critical, because on its own it changes the decision. This is not about accusing anyone. As the note on the assumed recalls, the word describes the statement, not who made it. The question is how much of the number was measured and how much was presumed. If the land is also on the table, the note on what the property record does not tell completes the picture: the property record registers the soil, not the ore.
When the asset is still at the exploration target stage. Without enough research to estimate a resource, the rule only accepts a range of tonnes and grades. The useful question is another: how much research is missing for someone to be able to estimate.
When the decision depends on price, cost and license, not on geology. The category speaks of confidence in the quantity. If the project dies on freight, on the market or on the environmental license, knowing whether the resource is Measured or Indicated answers the wrong question. The modifying factors are what weigh there.
When someone expects the deposit to be certified. The ANM does not certify the declarations, and Valida's verification does not re-estimate the resource: it confronts the word with the method. Whoever needs a new estimate needs a qualified professional to produce and sign it. Asking this of the audit is asking the reviewer to write the book.
In exploration reports filed with the ANM before August 8, 2022, yes: art. 9 of ANM Resolution 94 orders the old measured reserve to be read as a Measured resource. In a document after that date, no. "Measured" qualifies a resource, the confidence in the quantity; "reserve" is only the part whose economic viability a study has demonstrated.
No. ANM Resolution 94 says that the Inferred resource "must not be converted to mineral reserve," and CRIRSCO and JORC say the same. With more exploration, it may be upgraded to Indicated, but the rules themselves warn that this is not to be presumed. In the deal's calculation, it enters as a possibility, not as stock.
No. The resolution states that the ANM "has no mandate as a certifying institution" of public declarations. The agency approves the final exploration report when the deposit is demonstrated, but Decree 9,406, art. 73, excludes the liability of the Public Authority for inaccurate or false data. The holder and the technical manager answer for it.
A qualified, experienced professional with the proper credentials, subject to a code of ethics (ANM Resolution 94, art. 7). Under the CBRR guide, the Qualified Professional registered with the commission needs 10 years in the profession, 5 of relevant experience and 3 in a position of responsibility. Name, relationship and conflict of interest go in the document.
None of the rules examined fixes a number or a distance. The CBRR guide says the category depends on the quantity, distribution and quality of the data, and calls classification "expert judgment." That is why the audit checks the professional's justification and whether the data supports it.
Before putting a price on the subsoil, the useful question is not how many tonnes the report announces. It is how many were measured, and who signs for them. Start by asking for the declaration split by category and the name of whoever signs it.
