Which elements are organically bound in coal macerals?
Article The laser microprobe mass analyser for determining partition...
Probably U and Au? May be also Ni and Cr. I am don't know about exactly coals, but I had often found U and Th in hard bitumens.
Besides that, I'd listen, that the main part of Au on Kumtor gold deposit (Kyrgyzstan), deposited in coals, is desseminated in organic carboniferous matter, and only 10-15 % of its resources are concentrated in calcite veins as native metal. So they have big problems with gold extraction from such coal ores.
Dear Pavel,
I found your answer to my question very interesting. I too have found Ni and Cr in closely associated macerals using the laser microprobe mass analyzer. As for U and Au, I have never found these elements using this instrument. But it may be a matter of high concentration of these elements such as you mentioned near ore bodies.
May be even not ore bodies itself, but geochemical specialization of rocks, forming frame of coal basin. There are some coal deposits in Kyrgyzstan and Transbaikalia, from which U was mined by extraction from coal ashes. These coal basins are framed by granites with U specialization. Moreover these coals may to contain very special U mineralization - http://www.mindat.org/photo-265992.html
What about bitumens, mentioned above, one of them is visible here http://www.mindat.org/photo-72661.html as black points in white feldspar. Specialization of this pegmatite is Nb-Ti-Zn-Pb-P, and this bitumen is the main concentrator of U and Th.
Another case is this http://www.mindat.org/photo-419094.html And again, it is similar, that the bitumen concentrate all actinoids of this pegmatite with Zr-Ti-Sr specialization. In any case it is the single observed uraniferous phase here.
What about Ni, on Khaidarkan Hg-Sb deposit in Fergana valley was found bitumen after burning of which was obtained ash (~0.5-0.3 mas.% of initial probe) composed by pure NiO. Probably Ni was present here as Ni-porphyrine form. It is known as mineral specie abelsonite.
Many coals of Ural contains elevated Cr concentrations due to abundance of ultrabasic rocks in the region. Cr-smectite - volkonskoite - was discovered as masses included in wood trunks and stumps transformed in coal. It formed exactly in coal from ground waters, and don't grow in surrounding sands and clay layers.
And, of course, usual Au concentration in coals is quite low. May be first tens of mg/t, not 2-5 g/t as it is on Kumtor deposit.
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