text: Almost two decades later, René Just Haüy introduced wooden crystal models to illustrate the two-dimensional drawings in the atlas volume of his "Traité de Minéralogie" (1801). For the production of crystal models, wood appeared to be much more convenient than clay. Especially pear wood permitted getting smooth faces, sharp edges and accurate dihedral angles required for the production of these three-dimensional objects. In general, the angular accuracy was very high and some models, especially those illustrating crystal twins and Haüy's figures of decrement, still appear as masterpieces of fine woodwork and carving. Skilful craftsmen such as Pleuvin, Beloeuf and Lambotin (to name only a few) became specialists in this field and the models they offered were highly esteemed.
  Between 1802 and 1804, Martin van Marum bought 597 of these pear wood models, 550 of these are still present in the collection of Teylers Museum. Each model is labeled, mentioning a number and the name of the crystal form. This set is the most complete collection of Haüy crystal models that still survives. That Van Marum was able to acquire such a unique collection was due to his networking. Van Marum allowed Haüy as a member of the Hollandsche Maatschappij, a nomination to which Haüy attached great value. Haüy mentioned this membership in all of his publications.
  After their introduction by Romé de l'Isle and Haüy, crystal models were increasingly demanded both by scholars for teaching purposes as well as by mineral collectors. The quality of the models improved due to the technical progress in their production. Several mineralogists and crystallographers started designing their own series of models. Although pear wood kept a prominent place, models were also manufactured using materials like plaster, cast iron, lead, brass, glass, porcelain, cardboard, etc.