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[chris]

The exhibit is organised by the Club of Mineralogy of Chamonix and his President, M. Pierre Bavuz. It presents some of the best specimens ever found at the former “gold” mine of la Gardette near Bourg d'Oisans in France. It is displayed until the end of the year at the Mineralogy's Museum of Chamonix.

Before starting the visit, a bit of history...

The old mines are located above Bourg d'Oisans at 1300 m of elevation on the municipality of Villard Notre Dame. The quartz veins are between 60 to 90 cm wide (sometimes larger) and run on about 500 m of elevation. They are included inside a thin layer of gneiss included itself inside Pelvoux's granite (BORDET P. et Cl., 1963).

[chris]

The oldest activity dates from 1717. Back then, Cristalliers seeking quartz crystals for stone-cutting mills around Geneva first spotted yellow rocks mixed with quartz. Analysis performed at Grenoble identified those yellow rocks as gold. This discovery led the King of France to order gold search in the mine around 1733. Baldy managed these workings turned out to be unsuccessful, as a later try in 1765.

The mines returned quickly to their first purpose : providing crystals to stone-cutting mills.

In 1767 the discovery of native silver at the Challanches' mines (on the other side of the valley) led to intensive prospection. In 1770, Laurent Garden, a native of the area, found native gold at la Gardette. He gave those samples to M. Binelli then director of the Challanches' foundry (fonderie d'Allemont). Benilli didn't believe the samples came from the mine. As a result no searches were initiated.

At the same time (mid 18th century) the mineral collecting hobby emerged in Europe. Less laborious and more profitable to the Cristalliers than collecting for stone-cutting businesses, it triggered a new activity : collectible mining.

In 1776, the mines of the area (the Oisans) where given to M. Frère du Roi (M. King's Brother), the future King Louis XVIII. In 1777, the new director of the mines, M. Schreiber from Germany, started to search the area for galena used then to ease the extraction of silver from the Challanches.

In 1779, depending on the sources, he was either contacted by Laurent Garden who brought him gold samples from the mine, or had the opportunity of seeing the samples brought to Binelli 9 years earlier. He then decided to visit the location. Mine's engineer himself, he identified the matrix of the samples as the same as the one of the mine. With the agreement of the Royal administration, he started an intensive gold search in 1781.

Again the result was disappointing and the search continued intermittently until it stopped in 1788. During all this time Schreiber sold collectible minerals from the mines, the profit being counted as mining profits as in his native home : the Sax. Even if the profit was minuscule compared to the cost (8000 francs of that time for an exploitation cost of 27371 francs), it allowed a good understanding of the geology of the area.

Around the 1800s, locals made some attempts which, mainly, remained unsuccessful. During the next century several companies tried to strike a bonanza at la Gardette, including a famous scam, involving some officials around 1898. Even if some found collectible minerals (including gold) the profits remained quite low and each operation never lasted long.

[chris]

After the 1900s, the mines were searched intermittently by collectors looking for quartz crystals and other minerals . In the 1960s, the Cristallier Roger Fournier from Chamonix, did an important work at the mines. It partly helped his friend M. Poty in the writing of the La Gardette part of his thesis about the growth of quartz crystals. Presented in 1967, it triggered a new interest for the former "gold" mine amongst collectors.

The closure of the mines :

On the 23rd of March 2005, the French Gendarmerie (= police) arrested 9 people in relation with an investigation regarding the illegal collect or possess of minerals from the mines. 6 were quickly cleared and released, while 3 others were released while staying under investigation. They were completely cleared in 2008 by the justice. This investigation triggered numerous comments amongst French collectors and a passionate debate of the future of the mines.

Mineralogy :

Muscovite, tourmaline, siderite, calcite, Baryte, pyrite, chalcopyrite, brannerite, aekinite, gold, azurite, malachite.

For more information, and more pictures, you can visit these links (in French) :

https://www.geoforum.fr/index.php?showtopic=4310
https://tchorski.morkitu.org/2/gardette.htm
(links normalized by FMF)

The mines being orphan mines (meaning without identified owner), the administration asked the BRGM (the French Mineralogical Bureau) to investigate a security closure of the mines. 3 studies regarding the environmental and technical issues were conducted between 1998 and 2003. After several consultations between state and local administrations, associations, and without potential buyer willing to take responsibility, the state administration decided to close the mines. All but 2 entrances were destroyed by explosives or completely blocked. 2 of them are sealed by concrete walls only allowing bats to get in and out.

Today only mineral specimens collected before the closure testify of the natural wonders found in this "could have been" gold mine.

[chris]

[chris]

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[chris]

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[chris]

The last specimens to complete this quick tour, but from my point of view the bests :
- Azurite / malachite on tetrahedrite.
- An amazing "hedgehog" of crystal clear quartz as attractive as a lighthouse at nightfall.

[chris]

I want to thank M. Pierre Bavuz and the Museum's team for allowing me to take pictures of this fabulous exhibit. If your are in the surroundings, a visit to the Museum really worth the detour.

Apart from those specimens from La Gardette there are beautiful specimens from the Mont-Blanc including a spectacular fluorite.

Bibliography :

* Journal des Mines, Vol 2, 1806, pages 112-113
* La Revue du Dauphiné, Vol 3, 1838, pages 38 – 40
* La croissance des cristaux de quartz dans les filons sur
l’exemple du filon de La Gardette (Bourg d’Oisans) et des filons du massif du Mont-
Blanc », Bernard Poty, 1967.
* “Concessions du Pontet et de la Gardette, rapport de visite et d'évaluation des travaux de mise en sécurité” BRGM 98-G-324, janvier 1998.
* “Bref historique du site de la Gardette”, Frédéric Delporte, https://www.geopolis-fr.com
* “Schreiber – Mémoire sur la mine d'or de la Gardette en Oisans”, Cahier du Château Saint-Jean – 2008 – N°5 – pages 76 – 78.

[Jordi Fabre]

"Superb" Chris, thanks!

More info about the Espace Tairraz here: https://www.mineral-forum.com/message-board/viewtopic.php?t=324