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Wooden crystal model illustrating Haüy's laws of decrement
Wooden model illustrating Haüy's laws of decrement


Krantz catalog number 18
Krantz catalog number 18


Krantz glass crystal model
Krantz glass crystal model


biscuit porcelain crystal model
biscuit porcelain crystal model


wooden models on display socle

wooden models on display socle
 
Early Crystal Models


Introduction
The first real collections of crystal models were produced by Romé de l'Isle. He actually offered sets of small (ca 3 cm) models made of "terra cotta" in order to stimulate the sales of the expensive 4 volume set of his book "Cristallographie" (1783). The models were manufactured by his co-workers Arnould Carangeot, Lhermina and Swebach-Desfontaines, who produced numerous large sets (up to 448 models in each set). 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. This instrument, that proved to be an invaluable tool in geometric crystallography, enabled the measurement of interplanar angles with a precision of about half a degree.

Almost two decennia 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.

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.

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.

Over the years, Krantz published numerous detailed catalogues of the collections he offered; they constitute a precious documentation.

In 1994, Ulrich Burchard edited detailed drawings (generated by means of the program "SHAPE") of the models of the Groth and Krantz main collection with an indication of the original stamped numbering. Two years later, the same author described the supplementary series together with an alphabetic listing of all mineral species in both collections. The two volumes devoted to this collection constitute an invaluable documentation for the collector in order to appreciate, to compare and to identify these fascinating objects.


References
  • Burchard, U. (1994, 1996) The P. Groth & F. Krantz collection of 743 crystal models 1880 and The supplementary collection of 213 crystal models of P. Groth & F. Krantz 1887 © Ulrich Burchard (Freising, Germany)
  • Haüy, R.J. (1801) Traité de Minéralogie. 5 Vols. Paris
  • Krantz F. (1913) Allgemeiner mineralogisch-geologischer Lehrmittel-Katalog für den Schulgebrauch. Katalog Nr 18. Zweite Auflage. I. Teil. Bonn [1913 and earlier editions]
  • Romé de l'Isle, J-B. L. (1783) Cristallographie, ou description des formes propres à tous les corps du règne minéral, dans l'état de combinaison saline, pierreuse ou métallique. 4 Vols. Paris
  • Schuh, Curtis (2007) Mineralogy & Crystallography: On the history of these sciences from beginnings through 1919. Tucson, Arizona
  • Touret, L. (2004) Crystal models: milestone in the birth of crystallography and mineralogy as sciences in Dutch Pioneers of the Earth Sciences. Ed. by R.W. Visser and J. Touret, Koninklijke Nederlandse Akademie van Wetenschappen, Amsterdam
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