There's an interesting story about Gilsonite in the book"Rio Grande Glory Days" by Gil Lanthrop. It seems that he was firing on the standard gauge when the train stopped at Mack. Noticing some gilsonite leaking out from one of the cars, they decided to see if that stuff would burn. They threw a shovelfull into the firebox. They were so delighted with the results that they thew in a bunch more. Later when they were on the way, Gil tried to shake down the grates and found they wouldn't move. Later a mechanic contacted Gil to find out what the hell he did to that engine. It seemed that the grates were covered with a substance that was as hard as porcelin and they were trying to remove it with a hammer & chisel.
Gil pleaded ignorance.
Regards,
Donald Foster