Could this be wad?

 We climbed up to the lowest level at the Seathwaite Graphite Mine - graphite being called wad in the old days.

These two rocks were lying around and seemed to be dark grey and crystalline. Could they be wad? The one on the left drew a nice line like a pencil. It had a measurable resistance with the contacts quite close that fluctuated between 500 and 1000 Ohms.

I had no pencil so back in Wigton I checked the resistance of a short pencil "lead"

So the pencil graphite has a much lower resistance but every other rock I've tested has a resistance so high that it can't be measured on the scale. It might well have been graphite.