Dinagat island is mainly underlain by a mafic and ultramafic rock assemblage known as the Dinagat Ophiolite Complex (DOC). The DOC consists of a residual peridotite, cumulate peridotite, gabbro, sheeted dikes and pillow basalts.

Chromite deposits in the island occur as pods, layers and irregular bodies within the ultramafic suite of the ophiolite. All deposits are enclosed within a serpentinized dunite aureole. Several ore textures are observed in the deposits: massive, layered, disseminated, nodular and orbicular ores. All textures are seen to grade into each other.

Petrography of chromite grains reveal the presence of silicate inclusions. These inclusions are thought to be contemporaneously crystallizing phases with chromite until probable changes in the system favored chromite formation and eventual termination of silicate crystallization. A change in pressure and/or temperature, an increase in SiO₂ or H₂O content, or an increase in fO₂ of the melt probably due to magma mixing or melt convection are some of the magmatic processes that might have triggered chromite formation. These processes are indirectly supported by the stability relations of the silicate inclusions as well as data from mineral chemistry.

Based on the structural interpretation, petrography and mineral chemistry, it seems that chromite formed in small magma pockets at the base of the main magma chamber and within fractures in the mantle sequence.