LAUSR

Abstract Ryonchon chromitite is located structurally in the Chongjin area, the northern part of the Korean Peninsula, which crops out at Chongjin terrane, the eastern end of the Jilin-Yanbian-Hambuk Fold Belt. We made on-site geological survey of this deposit and conducted the analyses on the investigated chromitite by means of microscopes, single crystal X-ray diffraction (SXRD) and electron probe micro-analysis (EPMA) to elucidate the phase composition, the chemical composition and the texture and structure of the chromitite. The chromian spinels from the study area are separated into four groups according to chemical composition of spinel as ordinary spinel-group minerals are. The studied chromites have different compositions according to their occurrences, which is not owing to the precipitation of different pararental melts but the subsolidus re-equilibration during the hydrous alternation. The massive/semi-massive unaltered chromite in chromitite from dunite have consistently low Cr (Cr#