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From Discovery to Mine: The Mining Lifecycle (PEA, PFS, FS)

A mineral discovery becomes a mine only after passing through a strict sequence of studies of rising confidence — scoping/PEA, pre-feasibility (PFS), and feasibility (FS) — each converting resources into reserves with tighter cost and engineering certainty. Here's how the mining project lifecycle works, stage by stage, and why most discoveries never make it through.

Educational note: This article is for informational purposes only and does not constitute financial or investment advice. Always conduct your own due diligence and consult a licensed financial adviser before making investment decisions.

The mining project lifecycle is the sequence a mineral discovery must pass through to become a producing mine: exploration and resource definition, then a preliminary economic assessment (PEA), a pre-feasibility study (PFS), a feasibility study (FS), followed by permitting, financing, construction, production, and eventual closure. Each stage narrows uncertainty and raises the bar for the next.

Very few discoveries make it all the way. Industry data tracked by S&P Global puts the average time from discovery to first production at roughly 15–18 years, and that gap has been widening, not narrowing, over the past two decades. Understanding where a project sits in this sequence — and what each study actually proves — is the single most useful piece of context for reading a company’s news flow, because the vocabulary a company uses (PEA vs. PFS vs. FS, “resource” vs. “reserve”) tells you exactly how much has actually been de-risked.

If you haven’t already, read What Is Mineral Exploration? The Process, Stage by Stage first — this article picks up where that one ends, at the point a discovery is confirmed and the economic studies begin.

What are the stages of the mining project lifecycle?

StageWhat happensTypical durationConfidence level
Grassroots explorationRegional targeting, mapping, geochemistry, geophysics1–5+ yearsNone — no resource yet
Discovery & resource definition drillingSystematic drilling to establish continuity and grade2–8+ yearsInferred → Indicated → Measured
Preliminary Economic Assessment (PEA) / Scoping StudyConceptual economic analysis, may use inferred resourcesMonthsLow
Pre-Feasibility Study (PFS)More detailed engineering and costing; minimum standard to convert resources to reserves6–18 monthsModerate
Feasibility Study (FS)Bankable-grade engineering, ~±10–15% cost accuracy target1–2+ yearsHigh
Permitting & financingEnvironmental approvals, community agreements, project financing1–5+ years (often overlaps with FS)—
ConstructionSite development, plant and infrastructure build1–4 years—
ProductionMining and processing ore, generating revenueYears to decades (mine-life dependent)—
Closure & reclamationDecommissioning, rehabilitation, post-closure monitoringYears, sometimes decades—

The stages don’t always run in a strict straight line — permitting and financing often overlap construction planning, and companies sometimes revisit an earlier study (running a second PFS after a scoping study disappoints, for example) rather than always stepping cleanly forward. But the confidence hierarchy is fixed: you cannot skip from a PEA straight to a mineral reserve declaration.

What is a Preliminary Economic Assessment (PEA)?

A PEA — sometimes called a scoping study under the JORC Code used in Australia — is the first formal look at whether a discovery could ever become an economic mine. Under Canada’s National Instrument 43-101 (NI 43-101), a PEA is defined as “a study, other than a pre-feasibility study or feasibility study, which includes an economic analysis of the potential viability of mineral resources.” (Cassels, 2023)

A few things make a PEA distinct from later studies:

  • It can use Inferred Mineral Resources. This is the lowest-confidence resource category, and a PEA is the only one of the three economic studies permitted to build its economics around them. A PFS or FS cannot.
  • It is explicitly conceptual. Costs, mine designs, and metallurgical assumptions are order-of-magnitude, often drawing on comparable projects rather than site-specific test work.
  • It cannot support a reserve. Regulators are strict on this point: a PEA result is not, and cannot be presented as, a mineral reserve, and companies must include language flagging that the economics are preliminary and uncertain.

A positive PEA is a genuinely useful signal — it tells you management believes there is a plausible economic case — but it is the least reliable of the three studies precisely because it leans most heavily on assumptions rather than measured data.

What is a Pre-Feasibility Study (PFS)?

A pre-feasibility study is the first study detailed enough to convert mineral resources into mineral reserves. Under the CIM Definition Standards (adopted by NI 43-101) and the equivalent JORC framework, a PFS — not a PEA — is the minimum prerequisite for declaring a reserve. (CIM, 2014; AusIMM)

A PFS narrows the range of engineering options down to a preferred mine plan and processing route, using resource categories no lower than Indicated (Inferred resources cannot be used in the economic analysis). It typically includes:

  • Metallurgical test work on representative samples, not just comparable-deposit assumptions
  • A defined mining method and pit shell or underground design
  • Preliminary environmental and geotechnical studies
  • Capital and operating cost estimates with wider error margins than a full feasibility study

Because a PFS is the gate through which resources first become reserves, it’s the study where the language in a press release shifts meaningfully — from “resource” to “probable reserve” or “proven reserve,” under the CIM framework’s direct correspondence between Indicated Resources → Probable Reserves and Measured Resources → Proven Reserves.

What is a Feasibility Study (FS)?

A feasibility study — sometimes called a “bankable feasibility study” (BFS) when its level of detail is sufficient to support project financing — is the final and most rigorous study before a construction decision. Industry guidance from AusIMM notes that a Level 3 (final) feasibility study generally targets a cost-estimate accuracy of roughly ±10–15%, though that accuracy is frequently harder to achieve in practice than the target implies.

A feasibility study typically locks down:

  • Final mine design and production schedule
  • Detailed metallurgical flowsheet and recovery testing
  • Definitive capital and operating cost estimates suitable for loan and equity financing decisions
  • Environmental and social impact assessments ready for permitting submissions
  • Often, offtake or marketing agreements for the product

Lenders and major equity investors generally expect an FS-level (or BFS-level) study before committing project financing, which is why the FS is frequently the point at which a junior developer either brings in a major partner, secures debt financing, or is acquired outright.

Why does it take so long to go from discovery to mine?

Longer than most people expect. S&P Global Market Intelligence, tracking a large sample of mines, found the average lead time from discovery to commercial production was 15.7 years across 127 mines it studied, with individual projects ranging from 6 to 32 years. More recent data shows this trend worsening: mines that began production between 2020 and 2023 averaged roughly 17.9 years from discovery, up from about 12.7 years for mines started 15 years earlier — an increase of over 40%. Gold projects tend to move fastest (around 15 years on average), while nickel projects have taken the longest (nearly 18 years). Jurisdiction matters enormously too — the same research put average lead times at around 27–29 years in Canada and the United States, compared with much shorter timelines in some other jurisdictions.

The reasons the timeline stretches out are rarely purely technical:

  • Permitting and environmental review now regularly take longer than the technical studies themselves, especially in jurisdictions with extensive consultation requirements.
  • Financing gaps — a positive FS does not guarantee capital is available on acceptable terms, and market cycles can stall a fully permitted, fully studied project for years.
  • Community and Indigenous agreements are frequently a multi-year, iterative process running in parallel with formal permitting.
  • Re-studies. A disappointing PEA or PFS often sends a company back to the drawing board — a new mine plan, a different processing route, or a search for higher-grade zones — before trying the next study level again.

How does drilling and logging quality feed into these studies?

Every study in this lifecycle is only as reliable as the data underneath it. A PEA can lean on inferred resources built from wider-spaced drilling, but a PFS and FS require the tighter drill spacing, verified assay QAQC, and consistent core logging needed to upgrade those resources to Indicated and Measured categories — the categories the CIM and JORC frameworks require before a reserve can be declared at all.

In practice, that means the geological database behind a project has to hold up to increasing scrutiny at every stage: consistent lithology and structural logging, traceable sample chain of custody, and a drill-hole database clean enough that an independent Qualified Person or Competent Person can audit it without finding gaps. Programs that build this discipline in from the first hole — rather than retrofitting it before a PFS — tend to move through the lifecycle with fewer costly re-drills and data-integrity delays. This is the specific problem Blue Butterfly’s browser-based core logging and cloud geological database is built to solve: one validated, exportable database from day one of exploration, so the data a company generates early is still usable, and defensible, when a PFS or FS comes due years later.

FAQ

What is the difference between a mineral resource and a mineral reserve? A mineral resource is a concentration of material with reasonable prospects for economic extraction, classified by increasing geological confidence as Inferred, Indicated, or Measured. A mineral reserve is the economically mineable part of an Indicated or Measured resource, demonstrated by at least a pre-feasibility study — it carries a higher bar of technical and economic proof, not just geological confidence.

Can a company skip straight from exploration to a feasibility study? Technically yes — nothing legally requires a PEA — but in practice almost every project runs a scoping study or PEA first, because it’s a cheap way to test whether spending on a full PFS or FS is justified. Skipping straight to an FS on an unproven concept is rare and risky.

Why can’t a PEA be used to support a reserve declaration? Because a PEA can include Inferred Mineral Resources — the lowest-confidence category — in its economics, and Inferred material has not been demonstrated with enough geological certainty to support mine-planning decisions. Regulators require at least a PFS, which excludes Inferred material from the economic analysis, before a reserve can be declared.

Does a positive feasibility study guarantee a mine gets built? No. A positive FS demonstrates technical and economic viability under the assumptions used, but construction still depends on permitting approval, financing, board and shareholder decisions, and commodity price conditions at the time. Many fully feasibility-studied projects remain unbuilt for years waiting on financing or permits.

How is a JORC scoping study different from an NI 43-101 PEA? They serve the same conceptual role and sit at the same low confidence level, but the two codes use different terms: PEA under NI 43-101 (Canada), Scoping Study under the JORC Code (Australasia). Both are lower-confidence than a pre-feasibility study and cannot be used to declare a reserve.

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