After my first delivery of recently split wood I decide to save it for next year and found a place that had aged split wood. It is 3 year old wood that was split two years ago and sold last winter as well. It is very dark but not rotted however there was a lot of sand and dirt on some of it. I brushed it off as I stacked it. There is a pile of black dirt and bark left where it was dumped. about 4 foot wide. Is this an issue as far as burning is concerned? I will brush off more sand as I pull it to burn. Its not on every piece.