1743-1822

French mineralogist considered the founder of modern crystallography. Haüy's mineralogical work was primarily morphological—seeking to describe and classify crystal structure through geometrical principles. He proposed that crystals of particular species are created by stacking constituent molecules (now known as unit cells) to form simple geometric shapes with faces having constant angles of inclination. Haüy also recognized that crystal species were limited because not all angles of inclinations are possible—the discontinuity principle.