Good day. Let me explain my setup briefly. I burn primarily charcoal, but I throw a few pieces of anthracite in on my grate above the tuyere before adding charcoal to keep the small pieces of charcoal from falling through (I designed my grate back when I knew nothing and as such, the openings are too big.) When I was cleaning it out the next day, there was an interesting looking piece of (presumably) coal left over, so I took it out and played around with it. It was white, like charred coal, but it just looked strange. I broke it apart and it was white all the way through. Usually the leftover coal is still black in the center, ALL the other ones from the same fire were, and they were similar size (nut coal). I asked a friend who knows far more about geology than myself, and he said he is confident that it is sandstone. Its very soft, like sandstone, but i cant break it with my hands like burnt coal. I know that all the pieces were black when I threw them in, so what gives? This makes me question the quality of the rest of the coal that I have. The brand is Franklin Anthracite if that helps. Poor quality pic, sorry, but it's one of the chunks left from when I broke it.  

Edited February 25, 20179 yr by Will W.
Added picture

Pretty much all coal has some "trash" in it and looks like you found a piece.  I can't see it clearly enough to judge if it was originally a piece of rock or a chunk of electrical insulator, or ????.  1 piece per bag is not enough to worry about, 1 piece per scoop and I'd complain to the folks selling it to me.  Finally things covered with coal dust often appear to be black to start and may appear different after being heated and "burnt".

This is the first time I've noticed any trash. I have never looked for it before though. I'm definitely going to keep a closer eye on the stuff now. If it turns out there's a lot of junk in there, I may have to switch brands (or just forsake anthracite completely.) That makes sense about the coal dust though, the fact that it was definitely black when it went in the forge is what puzzled me. Thanks for the reply. 

Good Morning,

Anthracite is poor smithing Coal, use Bituminous, some call it Metalurgical Coal or Green House Coal.

Trash goes in the Trash Can, unless, it burns and then it doesn't matter. Trash will come out with the Clinker!!

Neil

Late reply, just checked in. 

On 2/25/2017 at 9:44 PM, swedefiddle said:

Anthracite is poor smithing Coal, use Bituminous

All I can get my hands on locally is anthracite. Seems to do the job pretty well, and I don't use a lot anyways. I burn mostly charcoal.