This study is mainly focused on mineralogy and trace element contents of the 5 bituminous coal seams, upwards Cay, Acilik, Sulu, Hacimemis, and Kurul, from the Asma-Dilaver and Gelik underground mines in the Zonguldak Basin, Turkey. In addition, some properties of the Akalin seam from Karayigit (2001) were also used in the present study. The coal seams are located in the lower-middle part of the coal-bearing Kozlu Formation of the Westphalian A (Upper Carboniferous) age and are extensively exploited in the underground mines for mainly metallurgical cokes. A total of 43 channel coal samples that represent the whole coal thickness have been evaluated in the present study. The coal samples on an air-dried basis were characterized by variable ash yields and low total S contents. The identifiable minerals by X-ray diffraction in whole-coal samples include clay minerals (kaolinite, illite, and chlorite), quartz, calcite, dolomite, pyrite, and siderite. All calcite and dolomite, and some siderite and pyrite, were formed in cleat-fracture infillings. Calcite contents are much higher in the samples from the Asma-Dilaver mines than the Gelik mines, while their dolomite and pyrite contents are relatively lower. Accessory mineralogy in selected samples was determined with scanning electron microscopy (SEM) with an energy dispersive X-ray (EDX). Elemental concentrations of the coal samples analyzed using inductively coupled plasma-mass spectrometry (ICP-MS) are relatively low, and the majority have variations in their contents among coal seams. The seam means of elemental concentrations, except for trace elements Cs, Mn, Rb, and Th in some seams, fall within the ranges of values for most world coals. Some trace elements (Sc, Cr, Cu, Ga, Rb, REEs, Y, Cs, Hf, Ba, Ta, Nb, Th, W, Zr, U, Zn, Pb, Bi, Tl, Be, Mo, and Co) in all the samples correlate positively with the ash yields, indicating that they are primarily associated with mineral matter. The remaining trace elements As, Cd, Ge, Mn, Sb, and Sr have no correlation with the ash yield.