Before any company breaks ground on a new mine, it must pass through a sequence of increasingly detailed and expensive economic studies designed to answer one fundamental question: will this project actually make money? These studies — the Preliminary Economic Assessment (PEA), the Pre-Feasibility Study (PFS), and the Feasibility Study (FS) — appear constantly in mining press releases, and understanding the difference between them tells investors exactly how far along a project really is.
The Short Answer
A feasibility study is a detailed technical and economic assessment used to determine whether a mineral deposit can be profitably developed into an operating mine. Projects typically progress through three increasingly rigorous stages — PEA, Pre-Feasibility Study, and Feasibility Study — each using more site-specific data and offering greater confidence in the project’s economics.
Why These Studies Exist
Building a mine is one of the largest and riskiest capital commitments in any industry, often requiring hundreds of millions or billions of dollars and many years before generating any revenue. These economic studies exist to progressively de-risk that decision — testing a project’s viability with increasingly detailed and expensive analysis at each stage, so that the truly enormous capital commitment of actual mine construction is only made once a high level of confidence has been established.
Stage 1: Preliminary Economic Assessment (PEA)
The Preliminary Economic Assessment, sometimes called a scoping study, is typically the first formal economic study conducted on a mineral deposit, generally following sufficient exploration drilling to produce an initial mineral resource estimate. A PEA answers a conceptual question: how could this deposit best be exploited to maximize its economic return?
A PEA includes preliminary engineering alternatives for mining and processing methods, broad estimates of capital and operating costs, and other high-level economic parameters. According to Investing News Network, a PEA can take up to a year to complete. Critically, under both NI 43-101 in Canada and the JORC Code in Australia, a PEA is uniquely permitted to incorporate inferred resources — the lowest-confidence resource classification — into its economic modeling, provided the company has a reasonable expectation the result would be a profitable mine. This is a special allowance that does not extend to the more advanced studies that follow.
The Mandatory Cautionary Language for PEAs
Because a PEA can be based partly on inferred resources — which are, by definition, too speculative to support detailed mine planning — NI 43-101 requires companies to include specific cautionary language whenever they disclose PEA results, warning investors that the economics are preliminary in nature and that there is no certainty the PEA will be realized. Investors should treat every PEA-stage announcement with this caveat firmly in mind.
Stage 2: Pre-Feasibility Study (PFS)
A Pre-Feasibility Study is a substantially more detailed follow-on to the PEA, based on more extensive, site-specific drilling and engineering data. Unlike a PEA, a PFS can only use Measured and Indicated resources (and mineral reserves) in its economic modeling — inferred resources are explicitly excluded, reflecting the higher confidence threshold required at this stage.
A PFS refines the mine plan, processing method, capital and operating cost estimates, and overall economic case with considerably more precision than a PEA, and is generally used to determine the economic breakdown of the project and detail what deposit quantities and qualities would actually be mined and processed during the project’s life.
Stage 3: Feasibility Study (FS)
The Feasibility Study — sometimes called the Final Feasibility Study — is the most detailed and accurate of the three, representing the culmination of years of drilling, engineering, environmental, and economic work. A full Feasibility Study is generally the document a company’s board of directors, and any project lenders or financing partners, will rely on to make the final decision on whether to commit the capital to actually construct a mine.
A positive Feasibility Study typically underpins a company’s formal construction decision and any project financing arrangements, since lenders generally require a bankable feasibility study — one detailed and rigorous enough to satisfy the due diligence requirements of banks and other institutional lenders providing construction debt.
Why the Distinction Matters So Much for Investors
The confidence levels across these three studies relate to both the underlying geological knowledge of the deposit and the accuracy of the economic estimates — capital costs, operating costs, and other key financial assumptions. A company announcing a positive PEA is at a fundamentally earlier and more speculative stage than one announcing a positive Feasibility Study, even though both events often generate similarly excited press releases and headlines.
For investors, this distinction should directly inform how much confidence to place in any set of projected economics — a PEA’s numbers should be treated as a conceptual, best-case scenario worth monitoring but not relying upon, while a full Feasibility Study represents a company’s most rigorous and defensible economic case for the project, the one that lenders and boards are prepared to bet real capital on.
A Note on Terminology Consistency
It’s worth knowing that under NI 43-101, the terms “preliminary feasibility study,” “pre-feasibility study,” and “prefeasibility study” are all used interchangeably to refer to the same second-stage study — differences in hyphenation or wording don’t indicate a different type of study, according to Cassels.com.
Key Takeaways for Investors
- Mining projects progress through three economic study stages: PEA (scoping study), Pre-Feasibility Study (PFS), and Feasibility Study (FS)
- Each stage uses increasingly detailed, site-specific data and offers progressively higher confidence in the project’s economics
- Only a PEA can incorporate inferred resources into its economic modeling — PFS and FS require Measured and Indicated resources or reserves
- PEA disclosures must carry mandatory cautionary language under NI 43-101 warning that results are preliminary and not certain to be realized
- A full Feasibility Study is generally required to secure project financing and support a formal construction decision — it’s the document lenders rely on
- Always check which stage a project’s economics come from before evaluating any capital cost, production, or return projections in a press release
SOURCES
1. Investing News Network — What Are Prefeasibility and Feasibility Studies?: https://investingnews.com/daily/resource-investing/prefeasibility-feasibility-studies/
2. Cassels.com — NI 43-101: What Issuers Need to Know About the Economic Analysis of a Mineral Project: https://cassels.com/insights/national-instrument-43-101-what-issues-need-to-know-about-the-economic-analysis-of-a-mineral-project/
3. Bill Cara — What is the Difference Between a PEA, a PFS and a Final Feasibility Study?: https://www.billcara.com/help-you-invest/what-is-the-difference-between-a-preliminary-economic-assessment-pea-a-prefeasibility-study-pfs-and-a-final-feasibility-study-ffs/
4. Investing News Network — What is a Preliminary Economic Assessment?: https://investingnews.com/daily/resource-investing/what-is-a-pea/
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