I'm trying to figure out what Form Coal should be. I guess Terram, since it's mined?
Unfortunately , Coal is covered by Ignem , as it is the remains of earthbound fire spirits. 
Really? Source?
I'd have gone with Terram as well.
Let me apologise , i was having a go , as they say. 
It should be Terram , unless more learned folk say me nay.
Coal should be
either herbam if it is wood coal
either terram if from a coal mine.
wikipedia : "Coal is a combustible black or brownish-black sedimentary rock normally occurring in rock strata in layers or veins called coal beds or coal seams"
Why would it be ignem? people believe maybe?
Standard Coal contains no Ignem vis.
If mined with flint tools when Sagittarius is in the midheaven with Mars Ascendant ,
then a Magic Lore Roll vs an Ease Factor of 15
will yield a number of pawns of Ignem vis = Ignem Form Bonus + (Aura Rating)/02
Sounds mystical enough. Did you made that on the fly or is that published somewhere?
Xavi
Complete Bullshit , im afraid.
Lady Merlina has right
She is wrong about wood coal being Herbam though , nor is it sedimentary rock.
There is no wood coal in Mythic Europe.
Wood coal is the artificial coal made out of tree trunks in an earth oven, right? Charcoal. If it is that, it certainly exists in Mythic Europe. Dunno for more northern parts, but around here it was quite common since there are not mineral coal deposits available, and we do not have turf.
Cheers,
Xavi
Charcoal is the dark grey residue consisting of impure carbon obtained by removing water and other volatile constituents from animal and vegetation substances.
Charcoal is usually produced by slow pyrolysis, the heating of wood or other substances in the absence of oxygen.
The resulting soft, brittle, lightweight, black, porous material resembles, coal. (emphasis mine)
I think this is where the Herbam association , may come from , via wiki.
Maybe this is an British versus American difference in usage, but in American "coal "comes out of mines and is definitely Terram. "Charcoal" is the little man made chunks that you throw on the barbeque to cook your burgers. Those are made of wood, therefore Herbam.
I'd say its either one and both at a lower magnitude.
Mist and vapor: Air and water
Ice: water and earth
etc
hope this helps:
en.wikipedia.org/wiki/Classical_element
I'm sure there are Bonisagus magi that make lots of these:
en.wikipedia.org/wiki/Hasse_diagram
Aura/2, rounded up or rounded down?
Come on Ravenscroft, you gotta quote the rules precisely. 8)
Read this thread for the second time. I think ravenscroft is making experiments with new drugs.
Xavi
I don't get it...
It was all that lodestone sand , it unbalanced my humours.
I was lazy to check if English use a different word: charcoal. So not wood coal but char coal.