I have mapped areas of Bodmin Moor especially around Minions which was originally a mining settlement. Large parts have been mined until around 1900, but it is likely that there has been mining since prehistory.

Early mining, as least medieval, was largely based on streamwork. This is described here (https://historicengland.org.uk/listing/the-list/list-entry/1020051). That describes a particularly large example near Minions. This website (https://www.aditnow.co.uk/Photo/Gonamena-Tin-Streamwork_50013/) includes some photographs.

As seen in those pictures, the ground is heavily disturbed. That case is fairly extreme. Often the area is smaller, but usually following a stream, and only a few metres deep. Frequently the ground is sandy with fine gravel, presumably from the extracted waste. Actually that is true in places at Gonamena, and it is also true of other smaller workings around Minions.

We don’t (yet) have any good tagging for these places, but I had used landuse=surface_mining which I think captures these distinctive areas quite well. Together with disused=yes. Unfortunately another mapper decide to change that tagging to landuse=quarry which is just plain wrong.

I have now changed to historic=mine (I am not keen on that) and landuse=disturbed (also not really a landuse) until someone comes up with better ways of capturing these special places. Perhaps I might change historic from mine to surface_mining.

There is a thread on talk-gb@openstreetmap.org about this.