Drill core samples from a lignite-mudstone succession with variations in organic matter maturity from Troyanovo-3 Mine (Mini Maritsa Iztok EAD) were analyzed for trace element contents. All elements except Hg and Th show one positive spike in their distribution, located at different depths. Molybdenum and Ni peak at the deep level (52.6–3 m); Fe, V, As, Hg, Zn, U, and Th peak at 29.3–29.5 m; Pb and Cu peak at shallow depth – 19.2–20.1 m. All measured concentrations are much higher than the Clarke for low rank coal and sedimentary rocks and comparable with published data for black clays from Troyanovo-3 Mine. The lack of significant correlation between total organic carbon and all analyzed trace elements points to other hosts for the trace elements. The strong positive correlations found for Fe and V, Ni, Cr, As, and Mo suggest incorporation of these elements into Fe sulfide phase(s). The strong positive correlations for Al and Ni, Co, Mo and U, and a weak correlation between Al and V suggest a terrigenous and/or sorbed form of presence. The lack of a strong correlation between mercury and total organic carbon, ash, sulfur and uranium confirms the well-known complex Hg affinity. Our previously outlined hypothesis for OM enhanced maturity as a result of ascended hydrosulfide injection is here further supported by the trace element differentiation at different depths.