Not sure where I got this from.Coal quality is measured by a...

Not sure where I got this from.

Coal quality is measured by a number of parmeters:
Ash - unburnable part of coal, 4.5% - 9%, average 5%.
sulphur - 0.2% - 0.7%, average 0.3%.
BTU (heat value) - 8,000 - 11,000, average 8,500.
Other trace elements: sodium, phosphurus, clorides, nitrates, sulfates, arsenic impact in various ways.

Direct comparison is hard because there is no standard of reporting. E.g. kcal/kg * 1.79 = 1 btu/lb.

Coal mining has been going on for yonks, so better grades coal have been taken out. As time goes on, we would expect lower quality to be mined. Again, one cannot compare current resource to those 20 yrs ago.The real yardstick is what the market is prepared to take and pay. With two companies chasing after this asset, it is not hard to conclude.

In terms of heat value, REY 5000+ kcal.kg is about average.