High-Cr and high-Al chromitites from the Sagua de Tánamo district, Mayarí-Cristal ophiolitic massif (eastern Cuba): Constraints on their origin from mineralogy and geochemistry of chromian spinel and platinum-group elements

► Two types of chromitites with different PGE and PGM contents. ► High-Cr chromitites and host dunite derived from a boninitic melt. ► High-Al chromitites formed in equilibrium with back-arc basin basalt melts. ► Crystallization of chromite accounted by mixing/mingling of melts. ► The two types of chromitites were formed in a nascent back-arc basin.