In recent decades, the Trimouns quarry has become well known as a source of outstanding crystals of several rare earth element-bearing minerals, including familiar species such as allanite, parisite and bastnasite, as well as very rare ones such as hingganite, iimoriite and dissakisite. Beautiful micromount-size specimens are the rule, but attractive crystals of several species exceeding 1 cm have also been found. These minerals occur in dolomite vugs in a contact zone of the Trimouns talc/chlorite deposit, where large-scale mining for talc may now be approaching its end.
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INTRODUCTION
The Trimouns talc-chlorite deposit is a mineral locality of international significance, producing fine crystal specimens of rare earth element-bearing species including allanite/dissakisite, bastnasite, synchisite, parisite, hingganite and iimoriite. Also, Trimouns is the type locality for two recently described species, trimounsite and gatelite.
The deposit is located in the Ariege Departement of southwestern France, 6 km northeast of the village of Luzenac, 40 km (via Spain) from the Principality of Andorra, and 115 km from Toulouse. It lies at an altitude of 1800 meters on the west slope of the St Barthelemy massif, the peaks of Saint Barthelemy (2348 meters) and Soularac (2368 meters) towering above it. Because of the heavy winter snowfalls, talc is quarried for only 6 months of the year, from May through October.
The name Trimouns comes from the langue d'Oc words Tres Monts (three mountains), in reference to the three peaks that overlook the quarry. Langue d'Oc is a regional language of Latin origin; it is traceable to the Middle Ages and is still spoken today in southern France, in the region known as Languedoc--the equivalent in northern France is langue d'oil.
HISTORY AND MODERN WORKINGS
The Trimouns deposit was first described in print in 1841 by Engineer Francois in the Annales Agricoles Litteraires et Industrielles de l'Ariege. In 1905 the quarry was acquired by the Societe des Talcs de Luzenac (Mengaud, 1909); in 1988 it was purchased by the Groupe Luzenac, a wholly owned subsidiary of Rio Tinto Zinc (RTZ), the world's foremost producer of talc at 1.3 million tonnes per year. The quarry employed some 100 workers at the beginning of the 20th century, when the ore was hand-sorted (de Launay, 1913). Today the talc is quarried by modern hydraulic shovels, and the ultra-white ore is sorted by laser camera.
Trimouns, the largest talc occurrence in France, possesses estimated reserves of 16 million tonnes, sufficient for half a century. The quarry employs 300 people and is the largest talc-chlorite mine in Europe, producing more than 400,000 tonnes annually.
The ore is quarried both mechanically (85% of the tonnage) and manually from successive benches. The ore is then sorted, partly on the basis of their degrees of whiteness (see below). Each year 10.35 million cubic meters of waste rock are extracted by a 210-tonne mechanical shovel with a 25-tonne capacity bucket. The rock is loaded into 8 dumpers at a rate of 16 tonnes/hour; each dumper has a transport capacity of 120 tonnes/day.
The mine cars,...