Mining Data Methodology

Where the figures come from

For each company we identify the places it publishes to — its news releases, its technical reports, its financial filings and its current corporate presentation — and we keep a copy of each document we use. A figure on this site is always traceable to one specific document, which is named beneath it and linked where the company still hosts it. The passage the figure was read from is kept with it and can be opened from the same place.

We keep our own copy of each document, including tables a company publishes as a picture, so that a figure stays checkable even if the original page moves or is taken down.

What is checked before a figure appears

• Each reported value is looked for in the text of the retained document, so a figure cannot appear because it was inferred rather than reported.
• Every row must carry the unit the company printed. A cost of 18.40 is published as US$18.40 per ounce, and it is shown that way rather than as a bare number.
• A person reviews the figures against the source document and approves the period or the estimate before it is recorded. Where a value could not be verified automatically — most often a table published as a picture — the reviewer has to confirm it against the source explicitly.

Units, and the one place we rescale

A reported figure keeps the unit it was published in wherever it stands on its own, and we never convert between measurement systems or restate a grade: an ounce per short ton and a gram per tonne are different conventions, and a converted grade could not be checked against the report it came from.

There is one exception, and it exists because reports are inconsistent within a single table. A resource table commonly prints contained silver as “5,049 koz” on one line and “13,981,254 oz” on the next, which are the same kind of figure and cannot be compared by eye. In our tables each column of tonnages or contained metal is therefore shown in a single unit from the same family — silver in millions of ounces, gold in thousands, base metals in kilotonnes — chosen so the largest figure in the column reads plainly. Nothing is converted across families, and every rescaled figure carries the value exactly as the company published it, which you can see by hovering over it.

Large money figures are shortened in the same way where they are listed for comparison — US$17,295,158 as US$17.3M — and again the published figure travels with them.

Equivalent metals

A silver-equivalent or gold-equivalent figure restates several metals as one number, using the company's own price and recovery assumptions. It is not additional metal. Where a company reports one, we show it and mark it as an equivalent, and we never add it to the individual metals reported beside it. Different companies use different assumptions, so equivalents are not comparable between companies.

To value a resource on assumptions of your own rather than the company's, the resource calculator takes the reported tonnages and grades and lets you set the rest.

Subtotals and combined categories

Resource tables commonly print combined lines — measured & indicated, or proven & probable — alongside the individual categories. A combined line restates the rows it summarises rather than adding to them. We keep those lines as the report printed them and mark them, so they are never double-counted.

Historical estimates

A historical estimate is one that has not been verified to a current reporting standard such as NI 43-101, JORC or S-K 1300. Companies still cite them, so we show them, and we label them as historical. A historical estimate should not be relied on as a current resource or reserve.

Reported periods

A quarter, the year-to-date figure that includes it, and the full year can all end on the same day and are three different periods. Each is shown separately and labelled with the kind of period it covers; they are never added together.

When a company restates a period, the restated figures replace the earlier ones and only the current version is shown.

When the data is updated

We monitor each company's own publishing sources for new documents. When a document that carries mining data is published, the figures it affects are prepared for review; they appear here once reviewed. A quarter that a company reports in a news release and then restates in its later filing therefore shows the release first and the filing afterwards.

Nothing here is investment advice, and none of it replaces the company's own filings. Where a figure matters to a decision, read it in the source document, which is linked beside every figure on this site.