Yes, in a shallow tourist mine in Australia. Apparently coal starts to flake easily once it’s been exposed to air for a bit, so they kept a big chunk in a large jar of water that you could take out and handle. It felt like a light wet rock.

The sample, and the coal at the workface of the mine was stereotypicaly black. We wore hats with lights on, and when we emerged back out to the daylight I had an overwhelming urge to speak in a Monty Python type Yorkshire accent and go home and have my back scrubbed clean of the coal dust by my swarthy tired looking wife while I sat in a tub in front of the fire in the kitchen and our urchins played in the street.

I don’t want to give the impression I’m a big fossil fuel tourist, but I’ve also seen blobs of crude oil on beaches near Mediterranean sea oil terminals.

Sadly, I didn’t try to set fire to them on either of these occasions, which I now regret.