 Unprocessed M. x giganteus has strong fibers, making grinding into equally sized, very small particles (below 75 µm / 0.075 mm) difficult to achieve.Coal chunks are typically ground to that size because such small, even particles combust stabler and more efficient.While coal has a score on the Hardgrove Grindability Index (HGI) of 30–100 (higher numbers mean it is easier to grind), unprocessed miscanthus has a score of 0.