a mineral of the silicate class, named for the English geologist and mineral collector A. Hume (1749–1838); in structure, isolated Si0₄ tetrahedrons with (OH)⁻ and F⁻¹ anions attached. Chemical composition, Mg₇ [Si0₄]₃(F, OH)₂. Humite crystallizes in a rhombic system, forming small dipyramidal crystals and amorphous colorless or honey-yellow grains. Hardness on the mineral scale, 6–6.5; density, 3,100–3,200 kg/m³. Humite is found as a relatively rare mineral in contact-marbled limestones.