Don't get me wrong Neo, I'm all for adding new stuff to the game. Just make sure what you're adding makes sense I guess is what I'm trying to say. Having weapons made of magnesium or lead would be utterly retarded. Magnesium would shatter on contact with anything other then flesh, and lead would be ridiculously heavy to the point of worthlessness except maybe as a club or something.
After looking over your list again here are my suggestions to add to the pile you've probably received already:
-No radioactive metals. Who in their right mind would wield a weapon that gives them cancer?
-The evil materials don't seem like they would fit in the game very well IMO, but if you really want to add them then you also need to add some sort of lawful materials and then make wielding them change your allegiance to the gods in a way similar to Mjolak. Should be pretty easy to do and would make them actually unique.
-No mercury, because once again it makes no sense.
-I really like the idea of philosophical materials. You could do some very interesting things with that (love has a chance to charm, for instance).
-The other types of leather would be alright I guess, but don't go overboard. Maybe just add a Cured Leather or Embossed Leather or something since leather isn't used for very long in the game anyways.
-Coal is a great idea, and I don't know why it isn't in the game already. It could be a horrible weapon material, but it easily hardens into diamond with a scroll. Could be cool.
-The food materials are pretty interesting as well, but I'm not sure what their use would actually be. Care to elaborate on that?
That's all I have for now.