Quarries and mines — how this layer is made

What you are looking at

Each dot is a place where material is taken out of the ground. There are more than 300,000 worldwide. Colour represents which of four kinds it is, and the size of a dot represents the footprint of the site. Click on any of them to see what OpenStreetMap records, such as who works it and its website. If there's a Wikipedia article, we show a short summary and a link to the full article, in your own language where possible.

Where the data comes from

Every feature here is something a mapper added at the OpenStreetMap website, from a survey, from aerial imagery or from a hole they walked past. We don't model or estimate anything ourselves, and we haven't merged in any national minerals register. National geological surveys hold much fuller records, so this is what has been mapped openly rather than everything in the ground.

What we include

There is no single tag for an extraction site, so we assemble the layer from six:

`landuse=quarry` is an open pit, and it is four features in five. It is also the only kind normally drawn as an area rather than a point.
`man_made=mineshaft` and `historic=mine_shaft` are vertical entrances, more than 25,000 between them.
`man_made=adit` is a horizontal entrance driven into a hillside, more than 20,000 of them.
`historic=mine` and `industrial=mine` are underground workings, more than 13,000.

Several thousand features are two of these at once, which is not a mistake, because a working quarry with a shaft in it genuinely is both. We draw each feature in the first class it matches, in the order above.

Colour

Colour represents which of the four kinds a feature is, so it describes the shape of the thing rather than what happens there. Whether a site still works is the division most people want, and we can't show it. `historic=mine` sounds decisive and isn't, because mappers reach for it on operating sites too. OpenStreetMap has a way to mark a feature disused, and it is applied unevenly, so a legend built on it would state something the data doesn't support.

What lies underneath

A shaft or an adit is a point on the surface, however far the workings run behind it. One dot can stand for a single collapsed hole in a field or for many kilometres of tunnel, and nothing in the data separates the two.

Size

The size of a dot represents the footprint of the feature in square metres. Quarries are usually traced as an outline, while adits and shafts are nearly always recorded as a single point, because an entrance is a point on the ground and drawing it as one is right. We draw the untraced features at a small nominal size of 200 m², about the size of a traced adit. A quarry nobody has traced draws small too, so its colour tells you it is a quarry and its size tells you nothing. Among the traced features a typical one covers about 30,000 m², or three hectares. The largest is a lithium licence area over the Salar de Uyuni in Bolivia rather than a hole in the ground, and we cap the size scale far below it.

Where the map is empty

An empty area means nobody has mapped a working there, not that nothing was ever dug. Mapping is more complete across western Europe, North America and Australia than across much of Africa and central Asia. The most crowded view on the layer is North Wales, where slate quarrying left a density of pits, shafts and adits that local mappers have recorded thoroughly.

Up to date, mostly

OpenStreetMap is edited continuously, and we take a new copy once every one to three months. A quarry shown here may have been filled in and landscaped, and an adit may have been sealed for a century.

Source and licence

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