Watch how a company's mineral resource has changed across successive NI 43-101 reports — contained ounces, grade and tonnage — so genuine discovery can be told apart from reclassification and cut-off changes.
A resource estimate is a snapshot, and companies quote the latest one. What they rarely present is the sequence — how this estimate compares with the one before it, and the one before that.
The sequence is where the information is. “Two million ounces” means something quite different depending on whether the last estimate said one million or three. And a headline increase can be produced without any new discovery at all: reclassify inferred material into indicated, lower the cut-off grade so marginal rock qualifies, or fold in an acquired deposit, and the ounce count rises without a drill turning.
This tool lines up every resource estimate a company has filed and shows contained ounces, average grade and tonnage across them — so the question “did the deposit actually grow?” can be answered rather than assumed.
Contained ounces is the headline figure and the one companies lead with. Read it alongside the other two columns rather than alone.
Average grade is the critical companion. If ounces rose and grade fell materially, the additional ounces are lower quality than the original ones — often the signature of a reduced cut-off grade rather than a better deposit.
Tonnage completes the picture. Ounces are grade multiplied by tonnage, so a rise in ounces driven entirely by tonnage at falling grade is a different event from one driven by both rising together.
Category breakdown shows how much sits in each confidence class. Movement from inferred into indicated and measured is real progress even without a single extra ounce, because it means the geology is better understood and the material can be used in economic studies. Growth that stays entirely in the inferred column is the least valuable kind.
Report dates matter because they set the pace. A resource that has not been updated in several years suggests drilling stopped, which is usually a funding story rather than a geological one.
The best pattern is ounces rising while grade holds steady or improves. That means the company is finding more of the same quality material, or better — genuine discovery rather than accounting.
Equally valuable, and much less celebrated, is material migrating up the confidence categories. A resource moving from mostly inferred to mostly indicated has become usable in a feasibility study, which is the gateway to financing and permitting. Nothing about the deposit changed; what changed is how well it is known, and that is what turns ounces into a project.
Treat rising ounces at falling grade with suspicion. It is often legitimate — a lower metal price environment genuinely changes what is economic — but it is also the easiest way to manufacture a growth headline. Check whether the cut-off grade changed between reports.
Finally, set resource growth against share count growth. A company that doubled its resource while tripling its shares has gone backwards on a per-share basis, which is the number that actually determines your return.
Resource estimates are taken from filed NI 43-101 technical reports, grouped by project and ordered by report date. A single report typically lists several categories, which are combined for the totals and also shown separately so the confidence mix is visible. Only companies with resource estimates on record can be charted.
The limits worth knowing:
Several ways. Reclassifying inferred material into indicated or measured raises the confidence categories without adding ounces. Lowering the cut-off grade brings previously uneconomic rock into the estimate. Raising the assumed metal price has the same effect. Acquiring another deposit adds ounces outright. All produce a larger headline number, and none require a drill to turn.
Because ounces are grade multiplied by tonnage, so the same ounce increase can mean very different things. Ounces up with grade steady means more of the same quality material. Ounces up with grade materially down usually means lower-quality rock has been brought into the estimate, most often through a reduced cut-off grade.
Yes, and it is undervalued. Inferred material cannot be used in a feasibility study, so it cannot support financing or a mine plan. Converting it to indicated or measured makes it usable — the deposit has not changed but its economic status has, which is the step that turns ounces into a project.
A resource is a statement that mineralised material exists in a defined quantity and grade. A reserve is the portion of it demonstrated to be economically mineable under a specific plan, with the necessary studies and permits behind it. Resource growth does not imply that anything will ever be extracted.
There is no fixed schedule; updates follow meaningful drilling. A gap of several years usually indicates that drilling stopped, which more often reflects the state of the treasury than the state of the geology. A steady cadence of updates suggests a funded, active programme.