S-K 1300 Explained: How US Mining Disclosure Finally Caught Up

Summary box

• The SEC adopted subpart 1300 of Regulation S-K on 31 October 2018, replacing the decades-old Industry Guide 7.
• Compliance became mandatory for the first fiscal year beginning on or after 1 January 2021, with earlier voluntary compliance permitted.
• The headline change: US registrants can now disclose mineral resources. Under Industry Guide 7 they generally could not — only reserves.
• Material properties with disclosed resources or reserves require a Technical Report Summary (TRS) prepared by a qualified person.
• Practical consequence: US-listed miners have a much shorter public history of resource reporting than TSX and ASX peers, and pre-2021 US filings are not comparable on resources.

What changed, and why it mattered

For most of the modern era, US mining disclosure ran on Industry Guide 7, a framework that predated the international codes and diverged from them sharply. Its defining feature was that SEC registrants generally could not publish mineral resource estimates. Only proven and probable reserves — material demonstrated economic under a historical three-year average price test — could be disclosed.

The result was structural. A company dual-listed in Toronto and New York could publish a full resource statement under NI 43-101 in Canada and be unable to repeat it in its US filings. Investors reading only the SEC documents saw a systematically smaller asset.

Subpart 1300 closed that gap and brought US disclosure broadly into line with the CRIRSCO family — the shared template behind JORC, CIM and the other national codes.

Per the SEC's own small entity compliance guide: "On October 31, 2018, the Securities and Exchange Commission adopted amendments to modernize the property disclosure requirements for mining registrants."

The timeline

That last row is the one that matters for anyone building a time series. For a large share of US-listed miners, the first annual report subject to subpart 1300 covered a year ended on or after 31 December 2021 and was filed during 2022. Resource data for US registrants effectively begins there. A chart of "US-listed resource growth" that starts before 2021 is measuring a disclosure regime change, not geology.

Classification under subpart 1300

The categories mirror the international codes:

• Mineral resources: Inferred, Indicated, Measured
• Mineral reserves: Probable, Proven

Terminology matches Canada exactly — Mineral Reserve, Proven, Probable — rather than Australia's Ore Reserve and Proved. Cross-exchange datasets need to normalise the Australian spellings; the US and Canadian ones already agree.

As with the other codes, inferred material cannot be converted directly into reserves, and conversion requires at least a pre-feasibility study.

The qualified person and the Technical Report Summary

Subpart 1300 requires that mineral resource and reserve determinations be based on information provided by a qualified person. Where an individual mining property is material to the registrant and resources or reserves are disclosed for it, the registrant must file a Technical Report Summary prepared by a qualified person, complying with the subpart. Item 1302 of Regulation S-K sets out the qualified person, technical report summary and technical study requirements.

Two differences from Canadian practice are worth internalising:

The TRS is not a Form 43-101F1 technical report. It covers similar ground and is organised comparably, but it is its own document with its own required contents. A company cannot simply refile its Canadian technical report to satisfy the SEC.

Qualified person independence works differently. NI 43-101 imposes an independence requirement in defined circumstances. Subpart 1300 permits the qualified person to be an employee of the registrant, subject to the professional and disclosure requirements. Where a TRS is authored in-house, that is permitted — and worth noticing.

The study ladder

Subpart 1300 recognises three levels:

• Initial assessment — the analogue of a Canadian PEA. It may support disclosure of mineral resources and may consider inferred material, but it does not establish reserves.
• Pre-feasibility study — the minimum basis for declaring mineral reserves.
• Feasibility study — the most detailed, supporting a construction decision.

Same principle as CIM and JORC: an initial assessment produces resources and an economic sketch; only a pre-feasibility study or better produces reserves. When you see a headline NPV on a US-listed developer, the first question is which of these three produced it.

Price assumptions: the quiet improvement

Industry Guide 7 tied reserve economics to a historical three-year average price. That anchored disclosure to the past and made reserves lag the cycle in both directions.

Subpart 1300 instead allows the qualified person to use a price they can justify — commonly a forward-looking or consensus estimate — with disclosure of the assumption. That is more useful and more dangerous at once: more useful because reserves reflect a defensible economic view; more dangerous because the assumption is now a judgment call that varies between issuers.

Always read the price deck. Two US-listed reserve statements built on materially different gold prices are not comparable, and neither is constrained to look backwards any more.

Comparing the three regimes

What this means in practice

For time series: treat 2021 as the start of usable US resource data. Any earlier US resource number is either absent or disclosed under an exemption.

For cross-listed issuers: the same deposit may appear in a Canadian technical report and a US TRS with slightly different numbers, usually because of price deck or effective date rather than geology. Check both before concluding anything about a restatement.

For screening: a US-listed miner with no resources disclosed pre-2021 has not necessarily grown. It has started reporting.

For diligence: an in-house-authored TRS is permitted and common. It is not disqualifying. It is a reason to read Items on data verification and metallurgical testwork more carefully than you would for an independent report.

How Mining Terminal handles S-K 1300 data

Mining Terminal ingests Technical Report Summaries from EDGAR alongside SEDAR+ technical reports and ASX public reports, normalising resource and reserve categories across all three regimes while retaining the source terminology and the reporting standard on each record. Study stage — initial assessment, pre-feasibility, feasibility — is a tagged field, because comparing an initial-assessment NPV against a feasibility NPV without it is meaningless.

Price assumptions and effective dates travel with each estimate. Where a filing omits either, the field stays empty rather than being filled from a sibling document.

To compare US, Canadian and Australian disclosure for the same issuer or peer set, get in touch or ask Nara.

Related reading

• Mineral Reserves vs Mineral Resources
• JORC Resource Estimates Explained
• How to Read an NI 43-101 Technical Report

Sources

• Modernization of Property Disclosures for Mining Registrants: A Small Entity Compliance Guide — U.S. Securities and Exchange Commission
• Final Rule, Release No. 33-10570 — SEC
• Voluntary Compliance with the New Mining Property Disclosure Rules — SEC
• 17 CFR § 229.1302 (Item 1302) Qualified person, technical report summary, and technical studies — Cornell Law School LII

This article is educational and is not investment advice. Mining Terminal is a data platform, not a broker, dealer or investment adviser.