La Gardette mine
45.0189° N, 6.0439° E · ± 10 km
Quartz from Isère, France, with photos of specimens from this locality.
Minerals found here
Quartz at La Gardette mine
Water-clear Alpine-cleft crystals with classic inclined-axis twins, associated with gold and brannerite.
- Formula
- SiO₂
- Morphology
- Elongated crystals with Dauphiné habit (one positive rhombohedron face dominant); lamellar growth in layers; geodes about 50 cm across and one several metres high in the main shaft
- Color / luster
- Transparent and colorless, smoky where in contact with brannerite
- Associated minerals
- Branneritenative goldchalcopyritebaritegalenasphaleritepyritetetrahedriteaikinite
- Twins
- Inclined-axis twins (Japan law, also called Gardette law) first described in 1829 and known for a long time only from this mine
- Availability
- Scarce
- History
- First gold mine worked in metropolitan France, with marginal gold output; worked mainly in the 18th and 19th centuries and stopped in 1901. The Atomic Energy Commissariat searched it for uranium in 1945 because of the brannerite. Its clear crystals were used in chandeliers at Versailles.
Geology of the locality
- Setting
- Alpine-type fissure (cleft) in gneiss, extending slightly into overlying Triassic sediments; fluid inclusions indicate growth around 330 °C and 2,000 bar
- Host rock
- Gneiss
- Region
- Isère
- Country
- France
Former gold mine in the territory of Villard-Notre-Dame, southwest of Le Bourg-d'Oisans; mining stopped in 1901 and the shafts have been largely backfilled. Coordinates are those of the Villard-Notre-Dame commune (Wikipedia), so position is commune level only.
Sources
- SRC-090 · Article
Filon de la GardetteAssociation Mineralogie Chamonix - SRC-091 · Article
SiO2 La GardetteEspacesTemps.net - SRC-092 · Website
Villard-Notre-DameWikipedia
Draft data from the Provenite workbook. Check entries against the cited sources before relying on them. Photos are open-licence images from Wikimedia Commons; the author and licence are given with each photo.