Ann: Quarterly Activities Report, page-54

Here is the link I use for the Newcastle Thermal Coal Price which is internationally used reference price. https://www.barchart.com/futures/quotes/LQ*0/futures-prices
Others can comment but discounts to the ICE price will apply to thermal calorific values below the ICE calorific specification . This discount applies to some of the lower calorific grades supplies by YAL which is a function of the partuicular operating mine. You will need to read YALs qtrlies and 6 monthly reports to see what I mean. But overall, I view the ICE price every morning ( pre-opening of ASX) simply to provide an indication of the dat to day price trend. An uptick in daily price from the previous day I guess will deliver a similar uptick in price for all thermal grades. From YALs announcements you see the mix of grades ( proprtions) and for the thermal grades can use the data to see ( over a period) what the average discount is relative to the average thermal ICE coal price for any given period. Bit of a slog, I have never bothered to do it.
Re metallurgical coal pricing , its all a bit opaque, although their is a site that provides some daa. I forget what it is, maybe another poster can assist