Feed coals, corresponding solid residues, and 18 sample sets representing the SRC, H-Coal, Synthoil, Lignite, Clean Coke, and COED liquefaction processes were investigated chemically, mineralogicaly, and petrographically. The data were evaluated from an economic viewpoint. Most of the 71 elements determined chemically, with the exception of Hg, As, B, S, Ti, Mg, and N, are generally retained in the residues. X-ray diffraction and electron microscopy analyses indicated that most mineral species remain unchanged during the liquefaction process. Mineralogical changes observed included the conversion of pyrite to pyrrhotite, the probable formation of metakolinite from kaolinite, and the collapse of some expandable clay minerals to a 10 A basal spacing. Microscopy of selected samples indicated that small amounts of solid organic particles, mostly vitroplast, are left in the residues. The chemical and mineralogical data, in conjunction with certain economic criteria, were utilized in a hypothetical economic evaluation of the minerals present in the residues as possible secondary sources for some metals. On the basis of 50 million tons of coal conversion, the value of 17 economically and strategically important metals was calculated, of which Al, V, and Ge were the most important.