Niels Steensen (in Latin, called Nicolaus Steno or Nicolaus Stenonius (1638–1686) and the cover page of his publication “De solido intra solidum naturaliter content”, 1669. – by studying the morphology of quartz crystals, he proved the constancy of interfacial angles - a discovery that marks the beginning of crystallography as a science.

Romé de l'Isle (1736 - 1790) and his work "Essai de Cristallographie", 1772 – he empirically confirmed the discovery of N. Steno by measuring other minerals using a contact goniometer and defined the First Law of Crystallography (which we know today as Steno's law) which states that the angles between the corresponding faces (and edges) of all crystals of the same substance, regardless of the shape, size and origin of the crystal, at same pressure and temperature are CONSTANT.

René-Just Haüy (1743.-1822.) i crteži iz djela, "Traité De Minéralogie", 1801.- observations of the cleavage properties of minerals spurred the development of the understanding of crystal structure. René Just Haüy, a French mineralogist, published the work "Traité De Minéralogie" [Mineral Traits] in 1801. In it, he described the concept of molécule intégrante after he observed calcite cleavage breaking into smaller and smaller pieces.

He observed that though they were of different sizes, all the cleavage faces were parallelopipeds with parallel pairs of faces and an equal angle between the adjacent faces. He concluded that with further cleavage one would reach the smallest parts, the integration unit which, if laid out in a specific manner in space would form different crystal forms of the mineral calcite.

Illustrierte Mineralogie, author: Adolf Kenngott. Stuttgart: Verlag von J.F. Schreiber, 1888 – this fantastically illustrated book is the work of renowned German mineralogist Gustav Adolph Kenngott (1818–1897). The author outlines the most important aspects of his work and states it is intended for the “visual instruction of youth in schools and families” (“Anschauungs Unterricht für die jugend in schulen und familien”). In addition to the many detailed illustrations, printed using the coloured lithography technique, the book is also significant in that it has remained in its original painted binding.