Geometrical cristallography

 

Domenico Gugliemi (1655 - 1710) recognised in 1701 four main outer shapes for salt crystals.

 

Cappeler in 1720 recognised 9 principal outer shapes among the crystals.

 

Henckel published in 1725 his book : " Pyritologie or natural history of pyrite " inside which he indicated some relations between mineral kingdom and vegetable kingdom.

 

Karl von Linneus or Linné (1707 - 1778) realised in 1730 several paper models of crystals and published his work " Systema Naturae ".

 

Wallerius gave in 1740 his explanation of the origin of various outer shapes of crystals and crystals groupings.

 

Gehler recognised the importance of the description of the external characters of crystals.

 

Westfeld emitted circa 1760, the hypothesis that calcite crystal is made of juxtaposed small rhomboedrons.

 

Linneus admitted circa 1760 the importance of the morphological study of the crystals and carried out crystal drawings.

 

Jean-Baptiste Romé of Isle (1736 - 1790) published his " Traitise on crystallography " in 1772; one owes to him the demonstration of the constancy of the dihedral angles between faces of crystals of a same mineral species.

 

Bergman emitted circa 1770 the hypothesis that different crystal outer shapes can derive from a same parallelepipedic core made up of superimposed plates.

 

René-Just Haüy (1743 - 1822) published in 1784 " Theory on the structure of the crystals " and in 1822 his very significant " Treaty of crystallography ". He is regarded as the father of crystallography thanks to his law of rational truncations and with the rigorous writing of the rules of symmetry, which allow the distinction between the 7 crystal systems including some secondary outer shapes.

 

Circa 1830 is introduced the use of the Miller's notation of crystal faces; a few later it will be generalised.

 

Frankenheim defined circa 1830 15 derived primitive networks.

 

Rose published circa 1840 his study on crystallography of quartz.