Structures of metallic elements 6.
ALL Compounds are Solids under suitable conditions of temperature and pressure.
Many exist only as solids. The alchemist Libavius recognizes that the geometrical habit of crystals is characteristic of the salts concerned 17th C ca. AX Formanek et al. AX Iijima - the first observation of point defects in structures by electron microscopy 1980s ca. An infinite array of points in space, in which each point has identical surroundings to all others.