Geodes and fumaroles: the minerals of volcanism
Exhibition carried out by Mr. Alain Martaud
> Mineral Zone > Exhibition area in Val d’Argent Expo
The destructive anger of the volcanoes was at the origin of legends and myths since antiquity. Vulcanoes were among the first places visited by naturalists as early as the end of the 17th century, and Earth Sciences, emerging in the 18th century, largely studied the accessible volcanoes as well as the rocks and minerals that make them up. This exhibition will show witnesses of the first mineral species described at that time.
A volcano is a set of rocks and earth and underwater geologic phenomena that result from the rise of magma (merging materials) and its eruption on the surface. The eruption may be caused by lava emissions, gas explosions, ash projections or underwater explosions.
We will try to make you discover more by displaying a wide variety of minerals coming directly from volcanism or after eruptions.
You will see the extremely rich paragenesis with the association of hundreds of mineral species coming from the Italian volcanoes Vesuvius and Lazio. Dozens of new species have been described, beginning with the famous Vesuvianite.
We will also introduce you to geodes from the north of Scotland to the Rio Grande do Sul on the Brazilian-Uruguay border, that offer the amazing spectacle of amethyst crystals with zeolites or extraordinary crystals of calcite, true crystal swords. Brazilian mining companies are very kind and lend us specimens longer than one meter, lined with crystals and resembling sumptuous sculptures.
At the other end of the world, in the area of Bombay in India, numerous basalt quarries are mined, that are packed with extravagant minerals: the zeolites!
Other volcanic flows, of different chemical nature, are the places of discovery of agate nodules such as the lythophyses of the Esterel in the south of France. Their delicate designs can be compared with those of the agates of Uruguay or those found as early as during the 17th century in Idar-Oberstein, Germany, which are at the origin of a whole artisanal and artistic tradition of gemstones and jewel cutting.
You will also encounter various ‘exotic’ volcanoes that from the South Atlantic to the South Pacific and even Antarctica are full of minerals like the anorthite crystals of Mount Erebus or man-made artefacts cut in obsidian from the Easter Islands.
These are some of the wonders from Africa or the Americas, which we offer, to bring to light as well as many others in the exhibition ‘geodes and fumaroles’. An incredible world to discover…
Photo text: basalt peridot knots in, originated from Ardèche, Rhône-Alpes, France
Left photo: opal knots of different colors in an ignimbrite, originated from Mexico, width: 12 cm
Photo right: red beryl from Wah Wah Mountains, Milford, Beaver Co., Utah, USA
Credits: © Éloïse Gaillou for the Musée de Minéralogie MINES ParisTech
The collections of: Museum National d’Histoire Naturelle de Paris, Musée Minéralogique de Mines ParisTech, Musée minéralogique de l’Université de Strasbourg, London Natural History Museum, Sapienza – Università di Roma and many private collectors.