While loading my 5 gallon bucket tonight. I came across a few lumps smaller than others in size, but much heavier. Why is it that some lumps are significantly heavier than others of comparitable size?
I've also came across what looks like slate, which will not burn! It glows very red when heated but will not burn nor really break when stabbed with my poker. Of course I don't burn it, usually these pieces get tossed out. No biggie.
It also seems like flatter pieces that appear to be harder than other coal, roughly 2 inches thick and maybe 6 inches by 4 inches sometimes refuses to burn. My dad who only hauled coal to power plants by semi for 20 years, and never burned it, calls it "bone coal" and says it's "trash coal" hahaha.. Are him and I the only ones that feel this way regarding the ugly flat pieces?