Make Vulcanus coal glow red

[h.q.droid]

The coal remains hard to see and even harder to distinguish from terrain decoration even after patching. I tried to mine out one 1k patch and it's literally invisible. Had to wave a big drill around to do it.

As an ultimate solution, I suggest making them glow red. It goes along with the general theme of burning carbon trees: if carbon were burning, coal should at least get red hot.