I have a gas fireplace that I have never used, but the people who lived here before I did obviously used it but never cleaned it. [Or, so it first appeared to me.] I'm now cleaning the fireplace prior to selling the house. I notice the "debris" seems to be a mixture of (1) something that looks almost like the insulation you would blow into an attic, (2) gravelly looking granules, and (3) what, at first, I thought was some kind of soot. On closer inspection, the "soot" appears to be sand. Originally, I thought this debris might be the residual of something that was burned on top of the ceramic logs. Now, I'm thinking it might be something that actually belongs there as some kind of insulation. Can anyone educate me?
There is material that is added to a gas fireplace and it is designed to appear as ashes while burning. It gives it a more realistic appearance. Don't remove it or pile it up, it is just for appearance. It helps the fire appear more 'real'.