Bauxite, rock largely composed of a mixture of hydrous aluminium oxides. Bauxite is the principal ore of aluminium. bauxite. Related Topics: ore laterite gibbsite boehmite diaspore. Gibbsite (alumina trihydrate), boehmite, and diaspore (alumina monohydrates) are the main ore minerals. Bauxite is a high-aluminum-content rock. Bauxite - Cement Grade Specification Parameters Percentage AL O : Min 36% Fe O : 34% SiO : 6% LOI : 20% Moisture 8% Size 0 to 100 mm Origin Maharashtra, India.