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You Signed it. You Own It. Responsibility in Ore and Minerals Reserve Estimates

February 3, 2026

Blog article by Allan Earl – Executive Consultant – Snowden Optiro

Understanding CP and QP responsibility in Ore and Mineral Reserve sign-off

Many Ore and Mineral Reserve estimates are signed off by a single Competent Person (CP) or Qualified Person (QP), most commonly the mining engineer responsible for preparing the mine plan, schedule, and reserve estimates. While this is standard industry practice, it places significant professional responsibility on one individual for a wide range of technical inputs and modifying factors, many of which may sit outside the CP or QP’s primary area of expertise.

Signing off a Mineral Reserve is not an administrative step

Signing off an Ore or Mineral Reserve estimate is not a formality. It is the point at which the CP or QP formally accepts responsibility for the Mineral Reserve and the assumptions that underpin it. By signing, the CP or QP confirms they are satisfied that the estimate is reasonable, appropriate, and defensible.

Responsibility extends beyond your core discipline

Although the single Ore and Mineral Reserve CP and QP needs to take responsibility within their own technical discipline, they are also required to critically assess and take responsibility for a broad range of other modifying factors. For a mining engineer, these commonly include:

Geotechnical inputs
Metallurgical testwork and recoveries
Hydrology
Infrastructure
Capital and operating cost estimates
Tailings and waste management
Acid and metalliferous drainage
Metal prices and treatment and refining charges
ESG considerations
Cashflow and financial modelling

Even where specialist input has been provided, responsibility for how those inputs are applied within the Mineral Reserve remains with the CP or QP.

Reliance does not equal responsibility

A common misconception is that reliance on specialist input transfers responsibility to the specialist. This is not the case. Responsibility for the Ore or Mineral Reserve always remains with the CP or QP who signs off the estimate.

The major international reporting codes are clear on this point:

JORC Code (2012)
A Competent Person may rely on specialist input where appropriate, but remains responsible for the conclusions and disclosures in the Public Report.
NI 43-101
Allows reliance on other experts only for specific non-technical matters and only with appropriate disclosure. Responsibility for core technical matters remains with the Qualified Person.
S-K 1300
Permits limited reliance on information provided by the registrant or other experts, but this allowance is narrow, conditional, and disclosure-based. It does not transfer responsibility for most technical inputs away from the QP.
SAMREC Code
A Competent Person may use and rely on specialist input, but responsibility remains with the CP.

Managing professional risk through critical review

To manage and reduce professional risk, the CP or QP must undertake a critical assessment of specialist inputs across the full mining value chain. This involves testing assumptions, understanding limitations, and ensuring that inputs are reasonable, appropriate, and defensible when applied to the Mineral Reserve.

What critical review actually means

Critical review does not mean re-doing a specialist’s work. Instead, it requires the CP or QP to apply informed professional judgement to determine whether specialist inputs are suitable for use in a Mineral Reserve estimate.

In practice, this typically involves assessing:

The criticality of the input and whether small changes could materially affect the Mineral Reserve
Whether the work is fit for purpose for a PFS or FS level Mineral Reserve
The competence and relevance of the specialist
Key assumptions and their reasonableness
Limitations, uncertainty, and associated risks
Consistency of inputs across disciplines
Appropriate application of the inputs within the Mineral Reserve
Clear documentation of the basis for acceptance

Owning responsibility for the Mineral Reserve

Critical review means understanding, testing, and correctly applying specialist inputs so that the CP or QP can confidently and defensibly accept responsibility for the Ore or Mineral Reserve.

More Information:
If you would like more information on how to critically review specialist input into Ore and Mineral Reserves, email contact@snowdenoptiro.com or Allan Earl at allan.earl@snowdenoptiro.com

Snowden Optiro is a resources consulting and advisory group that provides independent advice, consulting and training to mining and exploration companies, their advisors and investors.

We help mine developers to advance their projects, mining companies to improve their operations and their professionals, and investors to de-risk their investments by the provision of quality advice, training and software in the field of Mineral Resources and Mineral/Ore Reserves.

contact@snowdenoptiro.com