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Geologická sbírka École des Mines v Paříži

21.02.2010  |  22× přečteno      vytisknout článek 

Mineralogy, like the other natural sciences, is based on observation..

MUSÉE DE L'ÉCOLE DES MINES DE PARIS

Boulevard St. Michel 60, 75006 Paris, France

  THE NEED TO HAVE LARGE MINERALOGICAL COLLECTION

Mineralogy, like the other natural sciences, is based on observation ; now, apart from deposits, only collections can provide the numerous samples which will allow the study of the diverse properties, associations... of each species. In that respect, the Ecole des Mines is, in France, a perfect example.
 
The synthesis of crystals is currently on the agenda, but the Earth's crust is probably the synthesis centre offering the richest possibilities. Scientists sorely lack the time, taken in its geological sense. By want of collection and conservation means, we let most of these natural productions, resulting of physico-chemicals processes impossible to reproduce artificially, get wasted. Moreover, the development of modern mining exploitation methods makes the safe keeping of samples more difficult during works, and we also witness the accelerated disparition of the superficial layers of beds rich in well-crystallized species.
It is even more illusory to try and keep the minerals in situ, due to the necessities of mining exploitation, atmospheric alteration and vegetation for superficial beds, and also to the attraction of protected sites, which call the attention of "vandal amateurs" to them. Collections therefore constitute the sole safekeeping method for the samples forming the practical bases of mineralogy and numerous other related or derived disciplines.

In accordance to the spirit mentioned above, a modern public collection must include :
 

  • an exhibition of the best pieces, isolated in "jewel cases" or on stands, so as to exalt their beauty or strangeness, and stir or develop in the visitors the interest and taste for minerals
  • a didactic exhibition allowing the novice to quickly acquire the necessary knowledge for a more fruitful visit
  • and last, systematic collections, the working material for mineralogists, chemists and physicists alike, and reference material for amateurs.

THE "HÔTEL DE VENDÔME"

The mineralogy and petrography collections occupy the first floor of the "Hôtel de Vendôme", which housed the totality of the Ecole des Mines between 1815 and 1852, before this superb 18th century residence was defiled by disgracious extensions and last century's Great Works.
The so-called "Hôtel de Vendôme"  is the main relic of what once was the most popular convent in Paris, the Vauvert Charterhouse, founded by Saint-Louis and famous for its vineyard, the Clos de la Forge, on the location of which the School now stands !
From 1706 to 1707, the Carthusians, "under Le Blond's superintendence" had a great house built at the expense of Antoine de La Porte, canon of Notre-Dame (despite the legend, the architect was not Courtonne, but Jean-Baptiste Alexandre Le Blond, 1679-1719). The Hotel was rented in 1714 by the Duchess of Vendôme who had it modified to its present condition two years later by Le Blond. The Duchess, granddaughter of Grand-Condé, killed by alcoholism in 1718, is probably no prestige sponsor for the residence, better illustrated by the family De Chaulnes (who dwelt there from 1733 to 1758), and in particular by Michel-Ferdinand d'Albert d'Ailly (1714-1769), duke of Chaulnes. Member of the Academy of Sciences, he devoted his life to physics, and in particular to optics (Chaulnes's method, for measuring refraction indices) and measurement instruments ; like all scientists of the time, he was interested in the sciences of nature and his Museum of Natural History was in these surroundings the unfortunately gone ancestor of the present collections who, alone, let one admire the renowned suite of rooms of the "Hôtel de Vendôme".
Strollers walking though the South esplanade of the Luxembourg garden tread the ground of Le Blond's ancient garden, but unfortunately they can only glimpse, beyond a grille and disgracious greenhouses, a small and not well individualized part of one of the most beautiful residence of the Century of Lights.
The first floor of the "Hôtel de Vendôme" (where the mineralogy and petrography collections are presented) offers a setting  ideally suited  to the needs of a great modern mineralogic collection ; the long suite of rooms widely open toward the Luxembourg garden has been reserved to the systematic collections, as well as several sets of particular interest. The two anterchambers (Room A and Room B, also called Hauy Room), in which the elegant XVIIIth century allure has been preserved, have been devoted to showcase the most beautiful items, in the spirit mentioned before.
 
 

THE MISCELLANEOUS TYPE OF COLLECTION

THE SYSTEMATIC COLLECTION

Claude Guillemin who, from 1957 on reorganised and enriched the collection of the Museum of the Ecole des Mines de Paris, wrote : "One could easily let people believe that I, like too many curators, consider that the value of a collection lies only in its most dramatic samples. None of this is true ; I profoundly believe that, if exceptional items delight the heart of the collectors that, fortunately, most curators also are, and allow for a better understanding of the possibilities of the mineral world, yet they are but one of the dramatic and sometimes aesthetic aspects of the value of our collections, which must above all be an irreplaceable work instrument, always perfected for the sake of all scientists needing to refer to natural materials".

This quotation, taken from the preamble of the work headed "En visitant les grandes collections
minéralogiques mondiales " (C. Guillemin, 1972) is especially aimed at the curators who tend to neglect their museums' scientific value... to exclusively devote themselves to the hunt for the international collector's item, thereby forgetting that a museum curator is not only a great private collector. Fortunately, the persons in charge of the Museum of the Ecole des Mines have been wise enough, while implementing the necessary means for enriching the contents of the exhibition's showcases, to enlarge the purely academic patrimony of the initial set, an essential support for scientific works of all kinds. Thanks to an effort sustained over the last thirty years, aimed at creating exchange relationships whith laboratories, museums and collectors throughout the world, the museum can rightly pride itself for owning one of the most important systematic collections and one of the largest four collections of type species.

The systematic collection amounts to about 25,000 items, including the exhibited specimens. The number of mineral species explicitly recognized and well-defined can be estimated to around 3,300, but each species is represented, whenever possible, by several localities chosen among the most interesting ones. Of course, the rarest materials are ilustrated by only one specimen, whereas a species like calcite occupies several storage drawers. On the other hand, the museum keeps a great number of dubious or incompletely defined varieties and species. As a matter of fact, during a long part of their history, mineralogists have published a multitude of new descriptions, based most of the time on  chemical analyses, without any international concertation : the use of optical properties as an identification criterion only dates back to 1850, and that of X-rays to the beginning of the twenties, and this only for the better equipped mineralogy laboratories. As a result, about 20,000 names were given to varieties, mixes, artificial or redundant products. Only in 1959 the decision was taken to create, among the International Association for Mineralogy (founded in 1957) a commission in charge of examining the questions of mineralogic nomenclature. Today, the vast majority of descriptions of new species is subject to control by specialists from several countries, who decide by vote of its validity. A new species can only be homologated if the publication includes sufficient characteristic elements to justify its idividuality : precise chemical analysis,  optical properties, detailed crystallographic properties. Also, at least one type sample must be duly indexed in a museum. Three or four new species are thus described by French laboratories each year, and it is estimated that, during the period 1962-1983, 86 new minerals have been described by French authors (or with their collaboration), 23 of which originate from French deposits, among the 1146 accepted by the Commission in the same time for the entire world.

It is therefore necessary to keep and examine with current means the varieties and species insufficiently studied in the past, which can lead to new definitions, and even to the definition of new species - as happened already - originating from mines or deposits now exhausted or inaccessible.

 

THE TYPE COLLECTION

Whenever a new species is described, one calls "type sample" the sample(s) which allowed to specify its crystallographic, physical, chemical properties. Normally, bus alas only since recently, these samples must be deposited in a laboratory (or, rather, a museum) so as to ensure future conservation and access. In effect, if new specification studies needed to be undertaken on a given species, they could yield valid results only if  made on whole type samples or fragments of them, especially if these studies must lead to discrediting a species because it appears to be a mix or correspond to a preexistant species.
The categories of type samples to be used in descriptive mineralogy have been defined for twenty years or so ; this nomenclature is based on the degree of proximity with the holotype, which served to characterize the species. One can thus distinguish cotypes, i.e. samples used to complement the description, and metatypes, i.e. samples recognized by the author as identical to the holotype.
There are also "authors' samples" ; even today, as a matter of fact, authors sometimes send in samples without mentioning if these are the very sample(s) used for the description. This category is obviously  more frequent when the date of description of a species is older ; even if one is sure that a particular sample is coming from the author, it is often very difficult to attest that it was used for descriptive studies, except if the author or the person receiving the specimen wrote it down on the label, or if obvious relics of past experiments (fragments in tubes labeled "thin slices"...) accompany the sample. Under the term "dedicatory", we grouped the samples handed by the person to whom the mineral was dedicated. This category is of smaller interest, since nothing can prove, a priori, that the sample really corresponds to the material studied by the author.
A systematic search for type samples of ancient species was conducted after 1957 in the School's collections. We also keep most of the type samples corresponding to the species described in France since World War Two. Last but not least, thanks to a very patient work of correpondence and exchanges, we obtain very numerous fragments of type samples of the new species defined abroad.
All these samples, (for a total of 700 types of species or varieties) are kept separately and with particular care. The scientific importance of this collection led us to constitute a detailed catalogue published in 1983 for the bicentenary of the Ecole des Mines.

 

THE LOCALITIES COLLECTION

The most important numerically speaking, this collection is classified in the same way as the systematic collection. Its aim is to bring together the greatest possible number of different localities for a given species, partly to cater for the needs of researchers in the differents fields of science.
This collection, like all natural science collections, cannot be exhaustive. It would be absurd to try and bring together all occurrences of common species such as quartz, calcite, galena, ... but we try to bring together the maximum number of types of deposit and paragenesis.
 
 

THE DEPARTMENTAL COLLECTION

The departmental collection is a direct outcome of an arrest signed by the Public Salute Committee on July 12th 1794, establishing the Ecole des Mines in the Hotel de Mouchy, since the Mineralogy Cabinet  was to contain "all the productions of the Republic, arranged in the order of localities", and besides, the arrest signed six days before (18 Messidor An II) considered that one of the main occupation of mining inspectors and engineers was "to collect all the fossil substances like salts, earths, combustible stones, mines and metals that exist in their district, and to dispatch the propely labelled collection to the agency of mines in Paris".
An examination of ancien catalogues shows that this recommendation was very widely followed between 1794 and the end of the First Empire, several hundreds of samples, "products of art" and miscellaneous objects being received certain years.
We can mention for instance :
 

  • "samples from La Garonne copper mine near Toulon, handed on 17 Messidor An VII";
  • the same year, "yellow urane oxyde in groupes, lamelliform, quadrangular crystals from Marmagne, Saone-et-Loire district... handed by citizen Champeaux, mining engineer, who made their discovery" ;
  • some "wolfram from Puy-les-Vignes, sent to the coucil by citizen du Pallaud des Maisons on 23 Pluviose and 7 Ventose An 9" ;
  • lepidolite "found in rolled blocks in the fields on Chanteloube granitic plateau, 5 leagues north of Limoges", sent by M. Alluaud in 1811 ;
  • the collection of ores from Germany donated by M. Héron de Villefosse, "Inspector general of the mines and factories in the conquered lands" ...

The "statistical" collection remained thereafter dormant until around 1845, at which date, under Dufrenoy's influence, the galleries intended for them were restored and furnished ; then, between 1853 and 1864, de Chancourtois sorted it methodically, after having pruned all samples and objects devoid of interest "which cluttered the School" ; De Launay later took it over. Since 1957, the collection, in which only the minerals, the ores and a few rocks have been kept, occupy 250 drawers. 
  

THE GEMS AND METEORITE COLLECTION

The museum also keeps a collection of 700 gems (a part of the cut gems coming from the jewels of the Crown were attributed to the Ecole des Mines in 1887), 300 meteorites and artificial minerals.
As in many museums, the visible part of the set of items kept is not the sole interest of the museum of Mineralogy of the Ecole des Mines ; other collections of similar importance exist, but they need not be presented, being intended to fulfill different scientific and historical functions. Besides the exhibited collection, the museum houses the 20,000 samples of the systematic collection ; they are disposed inside drawers or cupboards, with inventory numbers referring to a collection-specific file. The 25,000 samples of the "localities" collection, also listed in a separated file ; a collection of 700 types, cotypes, and authors' samples, sorted in alphabetical order and recorded into a catalogue which has been published ; an important collection by French departments, which will need to be reworked and modernized ; a few hundreds of meteorites, cut gems and artificial minerals, only a part of which is on exhibition. It is also necessary to mention the existence of a series of showcases illustrating, with a few selected samples, the 1:320,000 edition of the map of France's mineral beds. A few showcases also present the new species described in France since 1950. Finally, a few shocases present temporary thematic exhibitions, such as Groenland's mineralogy, barytine in France, remarkable crystallisations... 

ZDROJ:http://euromin.w3sites.net, kráceno
 


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