Some problems you can meet...

 

What about fluorite?

The book "Valzergues fluorite mine"
E. Guillou-Gotkovsky
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Fluorite mining

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Gilles Emringer, collector

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Spathfluorminerals

 

Fluorite collections

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TRAPS TO BE AVOIDED

US VERSION (to be translated... thank you for your patience!!!)

 

The text presented here is not to make us play a role " upholders of the law" in mineralogy, but just to show you some modifications, arrangements or forgeries(imitations) which we are all susceptible to meet one day.

We can distinguish several categories:

The synthesis: take some common salt ( NaCl), dissolve some grams in some water (50ml and once the totally made dissolution, pour your mixture into a ramekin which you will forget voluntarily on the height of a cupboard, for example (immovable place - in theory!). When all the water will be evaporated, you will find beautiful small cubic crystals. The same system, in the industrial scale (and with techniques considerably more developed - Verneuil processing...) allows to form ruby crystals (used in lasers), diamonds (very small and used as abrasive for saws)... We saw, a few years ago, some crystals of copper sulphate which were spectacular but now forbidden for sale because of young children poisoning.

 

Artificial fluorite
Artificial fluorite
Fluorite(?????)
Specimen from Eastern countries. No location given!!!
In the crystal, germs are visible... They are the base of the crystallization.

Articial amethyste
Articial amethyste
Some doubts can remain: this amethyst is a man-made specimen but the identification is not easy.
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Monocrystal of synthetic quartz
Monocrystal of synthetic quartz
Monocrystal of synthetic quartz
Monocrystal of synthetic quartz - 20 cms length
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sulfate of aluminium and magnesium
sulfate of aluminium and magnesium
sulfate of aluminium and magnesium
Some are specialized in crystal synthesis and are doing business. Above, a sulfate of aluminium and magnesium which looks like some sulfur.
Everything is allowed since we tell the truth!

 

synthetic chalcanthite
synthetic chalcanthite

"Common" synthetic chalcanthite, made from copper sulphate II solution. The business would have been forbidden because of poisoning of young children who would have put the crystal in the mouth...

 

The irradiated specimen: It is a question of giving a more "commercial" appearance. The typical example is the morion quartz of Arkansas. Initially, it is white, crystal clear and after gamma irradiation, it turns black and brilliant. So, it is sold better thanks to some hours of human intervention... The natural irradiation, on the other hand, takes several thousand years: morion quartz of the "Massif Central", the alpine smoked quartz... How to recognize natural irradiated of the artificial irradiated? We are only giving tracks...

The warmed specimen: Classic phenomenon and "successful candidate" (under certain reserves, notably that to warn the buyer!) in gemology. The most common examples are:


- amethyst: which we put in an oven during some hours, and which sets one citrin colour. In fact, the heat in provoked a conversion of the Fe2 + ions , responsible of the purple color, in Fe3 + ions which give to the mineral the ochre-yellow color (intensity of the tint which is a function of the concentration in iron ions). The specimen is cut and sold thus then under the name of citrine logically, the salesman should clarify if it is about the natural or artificial citrine. What will not allow confusion, on the other hand, is the called, in French, "améthrine " stone which is partially purple and which presents another pole citrine. This mineral was formed in natural conditions and this is sure, because the means to obtain these two colors artificially on the same crystal, was not found yet!

- topaz: very blue, it is very possible that it was warmed. But there are blue topazes not warmed in sharply rarer quantity...

The examples are numerous...

The restuck specimen (in place): it occurs for specimens of big rarity, either those to whom the collector will attach a sentimental importance for example. Some pink fluorites of the "Mont Blanc" were restuck in place on quartz smoked on which they had developed. We can see also the example with the esmerald on gangue... The honesty would want that we indicate this repair during the sale. It's the same for specimen with strengthened gangue to avoid that all the specimen to be transformed into puzzle!

" Malachited" malachite
" Malachited" malachite

" Malachited" malachite! Some powder of malachite was stuck on the specimen which had defects (dings, breaks, damaged parts...).
The gangue is indeed malchite, and the superior layer also but between both, there is a small layer of glue!
hematite of Binen Valais-Suisse
hematite of Binen Valais-Suisse
hematite of Binen Valais-Suisse
A hematite of Binen Valais-Suisse. A specimen can stay for a long time in collection before the owner understand the trickery. Here, 3 roses of hematite (among 4!) were restuck by means of a cement made with the dust of the gangue of the mineral. The helping time (or not helping!), the color of the cement evolved and its texture also...
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The stuck specimen.. with different minerals (the "mineralogical medley"): we find them according to the mineralogical culture of the manufacturers. Indeed, some will not dare to associate a fluorite to an agathe!!!! But others will dare completely plausible more subtle associations: the association of 2 minerals of same format, but from different places...

crystal stuck on the gangue of garnets
crystal stuck on the gangue of garnets
crystal stuck on the gangue of garnets

The specimen is very aesthetic but the main crystal was stuck on the gangue of garnets. The joint was camouflaged with some powder of the gangue so that no smudge of glue is visible.

In the same genre and very common, we find the " Berber geodes ": these are geodes of chalcedony whose mineralogical interest is limited, and on which we papered the inside of galena cubes (different sizes for specimens more elaborated!). This is made by depositing a film of glue then by placing some cubes obtained by natural cleavage of the galena. The rest of the geode is then performed with residues of cleavage (powder) of the galène, which are going to stick in the not yet busy zones. It is the archetype of the "false specimen"...

Moroccan galena"crushed" stuck inside a geode of chalcedony
Moroccan galena"crushed" stuck inside a geode of chalcedony
Moroccan galena"crushed" stuck inside a geode of chalcedony
Just above: Moroccan galena"crushed" stuck inside a geode of chalcedony.
The galena was fixed there where the glue was, and sometimes the carpet of galena is not homogeneous (above right ).

 

 


A NUANCE:


The use of the natural cleavages: this is mainly visible with the fluorine. This one splits rather easily (with little knowledge of spliting!). From a cube, we obtain an octahedron. It is the major part of the octahedrons which are not on gangue, available on the market. The advantage is to be able to obtain a correct crystalline shape from a cube which was not useful because of knocks...

Octahedron of chinese fluorite
Octahedron of chinese fluorite
Octahedron of chinese fluorite. 3 cms edge. We can see zonations of colors which were paralells in the initial faces of the cube.
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The modified specimen: it is necessary to distinguish the the face and the back. Here, we only present the mineralogical interesting face (example: the crystallized malachite). On the other hand the work on the back of the specimen cannot be considered as a imitation.

About the modification of the crystallizations, this can be made by various chemical and\or mechanical means. An example was a quartz which had undergone some small shocks during its extraction. This specimen had an important value. To present it without showingit has been hand modified, some fluorhydric acid had been used to give a natural aspect to the breaks (*)

 

DO NOT MERGE WITH...

The work on the matrix(back of the specimen) : il nous semble indispensable de parler ici de ce travail qui peut être effectué avec plus ou moins de finesse, en fonction des moyens techniques dont on dispose.
Le collectionneur sur le terrain ne voudra pas s'encombrer de kilogrammes superflus, surtout s'il se trouve à bonne distance de son moyen de locomotion. Aussi n'hésitera t'il pas à user de ses outils pour faire partir un morceau de gangue. Si cela s'avère trop risqué, le travail pourra être fait à l'aide d'une scie diamantée. Mais il est vrai que certains n'apprécient pas de voir une pièce à l'envers bien droit et lisse. Cela se comprend.
C'est pourquoi il existe un système dit de "blastage" (sorte de sablage avec des grains plus ou moins fins), qui permet d'attaquer la gangue à l'endroit où elle a été sciée, pour lui redonner un aspect naturel (cassure, zone de contact...). Ceci n'est en aucune façon un "traffic" de mineral. Les marchands de tels systèmes sont bien représentés et présentent leur matériel sur certaines bourses internationales...

Le nettoyage des minéraux : Là aussi, certains puristes diront qu'un minéral ne doit pas être nettoyé, et présenté tel qu'il a été trouvé. Il est extrêmement rare de trouver un minéral qui ne soit pas sali, soit par des oxydes de fer, soit par de la "boue", ou bien par d'autres produits secondaires qui découlent de l'altération de la roche encaissante et qui sont plus ou moins tenaces. Une fluorine (par exemple!), aussi belle et brillante soit-elle, sous une couche d'oxydes de fer ne présente aucun intérêt. Pour cela des produits divers peuvent être utilisés. Le plus difficile est d'utiliser celui (ou ceux) qui n'ont pas d'action destructrice sur la cristallisation qui nous intéresse... La Revue "Le Règne Minéral" présente depuis le mois de juin 2004 des méthodes de nettoyage.

Nous parlions d'utilisation d'acides pour mettre en valeur des pièces minéralogiques. Certes, il peut y avoir une dérive comme mentionnée ci dessus (voir *), mais son utilisation est particulièrement bien adaptée pour dissoudre le quartz de certain échantillons qui seraient invibles sans ce procédé. A titre d'exemple, nous pouvons prendre les derniers octaèdres de fluorine chinoise qui sont initialement noyés dans le quartz. Leur couleur bleu-vert est ainsi mise en valeur. Mais ceci s'est également vu pour quelques rares pièces de fluorine et barytine du Maroc qui étaient dissiulées sous plus d'un centimètre de quartz marron, sale... et sans aucun intérêt minéralogique.

 

 

Ainsi, et nous le répétons, ceci n'a pour but que de developper un petit peu l'esprit critique du lecteur. Nous n'avons pas la prétention de tout savoir, mais nous tenons juste à informer quant aux surprises que l'on peut découvrir...

Par ailleurs, si vous êtes en posséssion d'un"faux" ou specimen qui n'est pas "conforme aux lois naturelles", vous pouvez aussi nous le faire savoir. Spathfluor se fera un plaisir d'enrichir cette rubrique... en restant discret, cela va de soi!

 

 

Remerciements aux collectionneurs qui nous ont confié leurs échantillons.

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E. Guillou-Gotkovsky© 2000-2011
23/11/08