The Mayari-Baracoa belt occupies the easternmost part of the east-west-trending Cuban ophiolitic belt. It comprises two large, chromite-rich massifs: Mayari-Cristal and Moa-Baracoa. Neither of these massifs show a complete ophiolite sequence, but they consist of a part of an ideal section made up of (1) harzburgites grading upward into interlayered harzburgites and dunites, (2) interlayered harzburgites (with minor dunites) and gabbros, (3) gabbros, microgabbros, dolerites, and diabase dikes, and (4) pillowed basalt, cherts, and radiolarites. Chromite deposits can be grouped into three mining districts according to the chemistry of chromite ore: the Mayari district and the Sagua de Tanamo district, both in the Mayari-Cristal massif, and the Moa-Baracoa district in the Moa-Baracoa massif. The latter is the most important as it contains more than 5.5 million tons of ore.