Dear Mr. Vörös:

The ratios mentioned by you  are controlled mainly by the detrital input into a coal-bearing environment and carbonaceous sediments. They are of relevance for the ash, the non-combustible part of the sedimentary rock.

I suggest the V/Cr ratio; both elements are indicative of different types of OM. V is mainly enriched in bituminous matter, whereas Cr is more abundant in coalified matter. The same result may be achieved with the Ni/Co ratio. Some elements can also be used on their own such as Mo, P, and U. The opposite effect may be gained using Zr, which normally increases along with the increase in detrital input. You may find some paper of mine on the RG Server. Chemical facies analysis is an efficient tool, but the procedure should be run in context with geology/sedimentology and mineralogy. You can also try and  calibrate it with organic chemistry and coal petrography. It is a highly versatile technique.

I wish you much success

Harald G. Dill

Dear Mr. Dill,

thank you so much for your advices. Don't you know, if is there any ratios commonly used in coal? I tried to create a graf. I put on the axis x V/Cr ratio and on the axis y Rb/Sr ratio. Could it this two ratios say something? I got a negative correlation with Pearson Coefficient only 0.11. Thanks in advance.