The raw material used to produce this product differs between coal and gilsonite:
Gilsonite is made from the decomposition of animals, but coal is made from the decay of plants and trees. Coal has a far larger calorific value and carbon content than Gilsonite, and the two may be separated using a straightforward test.
You can measure its solubility % in CS2; the greater the solubility, the closer it is to gilsonite, and the lower the solubility, the closer it is to coal.