Crystal model

In order to exactly transfer interplanar angles from natural crystals to the terra cotta models, Carangeot invented and designed a prototype of a contact goniometer.

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).

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.

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.

Although pear wood kept a prominent place, models were also manufactured using materials like plaster, cast iron, lead, brass, glass, porcelain, cardboard, etc.

Four years later, Krantz moved to Berlin and sold minerals, fossils, rocks and basically acquired a monopoly in the production of crystal models made of pear wood or walnut.

In addition, he sold a variety of glass models having the crystallographic axes illustrated by colored silk threads or with the holohedral form made of cardboard inside.