Approaching this from another direction, I think the nearest lead mines to Caernarfon were those of Dyffryn Nantlle.
Dave
Yes, my thoughts exactly. Closer to Caernarfon you are into copper veins.
The whole thing could be a flight of the imagination by the artist.
I tell you what though, take a look at the paintings reproduced in Chris Williams book of Mines Of The Alyn Valley, there is definitely a strong resemblance, at least to my eye. To be honest, it hit me right away. I am not an art expert but just suppose the painter J Ingleby (the book) and this guy are one and same.
If you want to take a look, the paintings are in the National Library of Wales
This is were someone tells me I talk poo, ah well.
My avatar is a poor likeness.