Looks like pea coal.
I had that problem once,my regular coal supplier(an elderly gent at the time)got sick and was closed for 2 weeks,leaving me to purchase my coal from another dealer.
This otheer dealers coal was a dark gray in color and sounded VERY HARD when you dropped it. I only had them put about a thousand pounds on my truck,and was I glad I did. It burned lousy. It took forever to get going and the only way I could get it to burn was high fire. I don't like that.
Try another supplier (just a small amount if you can) I would use nut coal, and make sure it's a nice deep black color and shiny like good ole Pennsy Blaschak anthracite.
Here's another tip, see if you can write on concrete with a piece of coal, I couldn't do that with the lousy stuff I bought several years ago. I mixed that crap in with my blaschak a little at a time when I got "the good stuff".
One bad load of coal can be a real pain.
Good luck, packard bill