I work near a coal facilty where turning trucks often spill coal onto the highway where It ends up at the edge of the pavement. I collected some for modeling. Then, I read somewhere that raw coal is toxic so I discarded it. However, in the Dec. 2013 edition of Railroad Model Craftsman, page 64, there is an article by Art VanWater titled "Making tender coal loads" where he uses" finely crushed coal." So... is real coal safe for modeling? - Brandon
As long as you aren't smoking it or inhaling large qualities of coal dust, it shouldn't be a problem. Depending upon the size of the found chunks, some coal makes great molds for limestone outcroppings.
I've been handling and burning it for years in the pacific. No problems yet except for that eye twitch. (just kidding ). There are a lot of volatile compounds in coal, so you wouldn't want to handle it and then eat. Using it in scenery or for a coal load is not a problem. Your adhesive that you use to bind it together could also make a shell over the load if you're really concerned.