A great collection of 11 glass crystal models, having the crystallographic axes illustrated by colored silk (Germany, early 1900's)

In 1833, Adam August Krantz (who studied pharmacy and later "Geognosie" at the "Bergakademie Freiberg") founded the "Krantz" company in Bonn. 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. Ever since its foundation, the firm was always in contact with renowned scientists and important collectors. Hence in 1880 Krantz proposed a series of 743 pear wood models compiled for teaching purposes by the crystallographer Paul Groth. Seven years later a supplementary collection of 213 models was available.

At the onset of the 20th century, Friedrich Krantz (a nephew of August Krantz, with a degree in mineralogy) supported by his teacher the crystallographer Carl Hintze, offered a collection of 928 models including most of the Groth models. Later, and along with many other productions, a Dana collection of 282 models was manufactured. Krantz offered a choice of collections of wooden models in different sizes (5, 10, 15-25 cm). 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. Also available were models in massive cut and polished glass (colored and uncolored), cardboard models, wire crystal models, crystal lattice models, models with rotating parts, etc.
In 1833, Adam August Krantz (who studied pharmacy and later "Geognosie" at the "Bergakademie Freiberg") founded the "Krantz" company in Bonn. 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. Ever since its foundation, the firm was always in contact with renowned scientists and important collectors. Hence in 1880 Krantz proposed a series of 743 pear wood models compiled for teaching purposes by the crystallographer Paul Groth. Seven years later a supplementary collection of 213 models was available.

At the onset of the 20th century, Friedrich Krantz (a nephew of August Krantz, with a degree in mineralogy) supported by his teacher the crystallographer Carl Hintze, offered a collection of 928 models including most of the Groth models. Later, and along with many other productions, a Dana collection of 282 models was manufactured. Krantz offered a choice of collections of wooden models in different sizes (5, 10, 15-25 cm). 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. Also available were models in massive cut and polished glass (colored and uncolored), cardboard models, wire crystal models, crystal lattice models, models with rotating parts, etc.

(info from the site: www.mineralogy.be)