Hard Substance on Firebrick?

Good, now I know what it is. Thanks, guys!!

Here is a pic of one from today. It was much larger when its in one piece. But this shows its thickness and its always in front of the doghouse. A nickel in pic for size comparison.

I am not a botanist. I assume that the silicas are dirt etc on the exterior of the wood - and not naturally found in trees?

nice pic dex

Yowza, that's a big'un. But yes, that looks like the same material; so now I know what a "klinker" is. Thanks, Dex!

i have yet to get a "clinker" in my cat stove, i have burned everything from oak at close to 40% MC to oak at lesss than 10%. I have burned seasoned pine as well as other hardwoods including maple sweetgum, poplar, hickory, never one of those, i wonder do yall all have tube stoves?

I don't thinks so...but what is a "tube" stove?

No clinkers here the last clinker i had was in my coal stove grate.

Sue, I doubt those chips in the corner of the brick are anything to be concerned with. Good luck.

Thanks, Dennis. However, it has certainly shown me not to clean the floor of the stove so "aggressively"

The only other type EPA stoves that exist beside CAT stoves. They have air "tubes" across the top to inject hot preheated air uptop to help burn the smoke.