UNFC groups every mineral deposit using three separate scales bundled into one three digit number. Think of it as a report card with three subjects: can we sell it profitably right now (economic axis), how far along is the mining project (feasibility axis), and how well do we actually know the rock (geological axis). A "1" in any subject is the best possible score, and the scores get weaker as the digit rises.
- 111: every subject scores a 1. The deposit is economically mineable today, the project has reached a confirmed development or production stage, and the geology has been drilled and studied in detail. This is the strongest, most bankable class UNFC has, matching what older reserve systems called a "proved reserve."
- 122: the deposit is still economic (E1) but the project stage and the geological detail have both dropped to level 2, meaning less certainty about when mining starts and how the ore body is shaped at depth.
- 333: all three scores sit at 3, a resource that has not been shown to be economic yet and is known only from early stage exploration, nowhere close to a proved reserve.
- 334: similar to 333 but the geological axis drops further to 4, the weakest confidence level UNFC allows, used for very early inferred resources.
Since every UNFC digit runs from strong (1) to weak (3 or 4), the single code built entirely from 1s, which is $111$, sits at the very top of the classification. No other combination among the four options can outrank it on any of the three axes.
Let's summarize:
- UNFC codes read as Economic-Feasibility-Geological, each axis scored 1 (best) downward.
- $111$ is the only option where all three axes hit the best score together.
So the highest category of mineral resource under UNFC is coded $111$.