I have a hunch that Group Theory discovered/predicted crystal lattices being the form of solid matter through point/space groups before we could inspect them indirectly with X-Ray Diffraction and directly with Electron Microscopy (and even Atomic Force Microscopy).

I guess I have to look into the history of atoms. And also molecules, though I’m not sure if crystals were part of these debates. It is also important to distinguish when history defines a molecule/crystal with respect to understanding protons/neutrons/electrons and quantum phenomena.


It seems that the history of crystallography is firmly delineated by 1912 - the invention of XRD.