It's not really a problem - that's the whole point of coal...

It's not really a problem - that's the whole point of coal quality monitoring.

It's strange they didn't pick this up earlier though. That should have been noticed during exploration drilling, never mind resource definition. It may be something localised to do with partial oxidation at the top of the seam or the upper seam may just be naturally lower quality.

Should be easy to find a solution by blending or possibly, if the whole upper 1.8m is poor quality, they might just discard the top metre or so of the top seam. Would still give them 9m of saleable coal.

As I said, not a major drama. It would be more worrying if this was happening in the export pile, but almost the only necessary quality for domestic grade thermal coal is that it burns.