Essai d'une Théorie sur la Structure des Crystaux, Appliquée a Plusieurs Genres de Substances Crystallisées

Paris: Gogué & Née de la Rochelle, 1784. First Edition. Near fine. Haüy’s first printed book, uncut in blue remnant wrappers, ink titled paper label, octavo pp. [viii], [1], 2-236, with eight folding engraved plates by Sellier after Fossier. Unrestored, clean, full margined and complete; a beautiful copy of a scarce book in wrappers. Custom slip case. Here Haüy established the theoretical foundation of modern crystallography through his revolutionary proposition that crystals are composed of identical elementary building blocks ("molécules intégrantes"). By observing how minerals cleave along predictable planes, Haüy deduced that this phenomenon (truncated) reflected an underlying structural order—an insight that explained why crystals maintain specific angles between faces regardless of their size. He proposed six fundamental primary crystal forms: parallelpiped, rhombic dodecahedron, hexagonal dipyramid, right hexagonal prism, octahedron, and tetrahedron. Haüy argued that the primitive form or "nucleus" of any crystal species could be revealed through the cleavage of secondary forms, though he considered this nucleus a mathematical concept rather than a physical reality. As Norman notes, Haüy "recognized the discontinuity principle; i.e., that not all angles and inclinations of crystal faces are possible, and therefore the varieties of a crystal species are limited."

Far beyond mineralogy, Haüy's treatise effectively introduced the concept of ordered atomic arrangements in solids more than 120 years before X-ray diffraction (von Laue) would provide direct evidence for such structures. His articulation of what would later be formalized as the Law of Rational Indices demonstrated that the planes of crystal faces relate to each other by small whole numbers, providing a unifying framework for mineral classification based on internal structure rather than mere external appearance. This conceptual leap connecting observable crystal forms to their fundamental molecular architecture earned Haüy recognition as the "Father of Modern Crystallography" and laid the groundwork for subsequent developments in solid-state physics and materials science. (Inventory #: 1143)