<p>Chongjin ophiolite, which is an on-land remnant of the oceanic lithosphere formed in the upper Paleozoic era, is located tectonically in the suture zone between the Sino-Korean massif and the Tumangang orogenic zone. To elucidate the varieties of chromite in the study area, their alteration textures and formation mechanism, scanning electron microscopy (SEM) and electron microprobe analyses (EPMA) were carried out. The results show that chromite grains exhibit two major microtextures: (1) alteration texture in massive chromitite, where the primary non-porous Al-chromite was partly or fully altered into porous Fe²⁺-rich chromites; (2) alteration texture in chromite-bearing serpentinite where the primary non-porous Al-chromite was partly or fully altered into porous ferrian chromites. The results also suggest that the chromite ore in study area underwent hydrothermal alteration under low-temperature (retrograde) metamorphic conditions before serpentinization. We established an alternative model of origin of chromite based on these results: First, early formed chromite reacts with olivine to form porous Fe²⁺-rich chromite and Cr-chlorite in presence of SiO₂-rich fluid. After that, more oxidizing Fe-bearing fluids interact with porous Fe²⁺-rich chromite in chromite-bearing serpentinite to form zoned or porous and non-porous ferrian chromite.</p>