Coal ID and "Used Coal" Question

Just wondering if anyone has any ID on the soft coal on the right. I bought it from a bulk supplier in cincy. burns ok, but doesn't really burn all the way down in alot of instances. That being said, can anyone tell me a little about the two nuggets to the left. The one on top was a whole chunk that I broke. Very hard, but brittle enough to crack by hand. The bottom one is very brittle and reminds me of lava rock in weight and texture. These came out of my stove after I let it die down for a day to clean out. It seems as though if I let them build up they will do just that, so I have to break it(my stove) down from time to time to clean the chunks out, to get good hot burns again.

The one on top left is organic shale/sandstone sometimes found mixed with coal, it will burn, but leave a lot of ash as your pic of it partially burned has told you. The piece on the bottom left looks like a clinker. If your furnace is making clinkers try using less underfire air, if you have a fan that feeds the fire when it calls for heat, this could be your problem; reduce the air intake on the fan to lower the speed and volume of air flowing through the fuelbed, this will bring down the fuel bed temp and eliminate clinkering. Is the coal you're using producing white, tan, pink, or orange/red ash? there's not much I can tell you about the coal pieces on the right - to tell you anything about unburned coal from a picture you're going to have to give me a VERY high resolution pic, having said that, if I was to guess, i'd say the top right is organic shale high in iron and pyrite and the stuff on the bottom right is lighter weight and more pure coal.

The pinkish piece on the top left if Definitely rock. I get these in my coal sometimes but most times you can break these up with a poker when hot so they will fall through your grates. If not I have a set of tongs to grab them out instead of letting fire go out. If you are careful you can minimize how many of these you put in stove by looking at your coal before loading. These will be alot heavier than just pure coal and will often be a different shape, more rounded. It is alot easier not to throw them in than try to fish them out after. The bottom left piece looks like a piece of coke. Coke is coal after all of the volatiles are burned off leaving almost pure carbon. Coke will burn with a nice blue flame and no smoke. The coal on the right is hard to tell without close up pics.

while the bottom left may be coke, i'm leaning towards clinker. Clinkers that look just like coke are rare, but certain coals will produce a porous "lava rock" type clinker from iron rich organic sandstone that resembles a lump of coke. It is very easy to tell the difference between the two when you pick them up, the coke will be very light and comprised of carbon, the porous clinker will be much heavier, contain no carbon and have the consistancy of grill "lava rock"

Clinkers will be formed, as I mentioned, from firing the furnace with too much air and burning the fuelbed too hot (excessive poking etc. from the top doesn't help) If you have a firebox with too much coke production, you're not keeping the fuelbed deep enough to maintain combustion of the much higher ignition temp coke.

The lava style rock is very light weight. Has the look and texture of a lava rock, but light as a feather.

It's kind of disheartening to hear the sandstone thought. As it seems if that is the case, than I have a pretty good amount mixed in with my coal. I included a few close up pictures that will hopefully have some more definition. For the most part my ash is a white/creamy color.

After further review of the ash. I will say that it is multiple colors. For the most part it's a white/creamy color. But there are also portion of light tan, and a real light pink color in some areas.

Thank you all so much for the help!

The two pieces of coal in the 1st photo(post with 3 photos)looks like coal with shale in it. The lighter grey color portion would be shale/rock and the coal around it will burn away leaving the rock which most likely will end up almost white in color like the white piece in the very first photo. Another indicator of rock is if the pieces weigh more than normal. If you tap on the grey part with a hammer it should be hard and sound different compared to tapping on the shiny coal part.
The "lava rock" piece could just be unburnt coal..? I would have to handle it to know for sure.
Maybe this was a bad batch of coal but before I would buy from them again I would try to inspect the coal...now that you know what to look for.
The coal in the other two photos looks ok to me.