Chert

And this is back to another era as well because in that, yeah, so there are a series of bowl-shaped pits which were used as small stone quarries during the Iron Age.

and also Romano-British and Middle Ages, primarily for extracting materials like chert, which they used for tool production, very much the way that flint was used to form scrapers and arrowheads and things like that.

Chert, similar, perhaps not quite so sharp.

And then they also quarried out greensand, which they made into querns, which are the hard stones that they use for grinding wheat so they get flour for bread.

Believe it or not, there are about 4,000 of these all over this area because it was basically sandstone.

I've been exploring abandoned mines since the late '70s.

As a preteen, my dad worked and looked after a chert mine in Bakewell.

Chert is a very hard silica-based stone, similar to a limestone and flint mixture, and it was used in the pottery industry.

Anyway, I digress.

Derbyshire is known for its lead mining history, and later fluorspar, which is a volcanic mineral formed millions of years ago.