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L'or des Pyrénées était connu des auteurs anciens et des recherches archéo-géologiques récentes l'ont mis en évidence sur le plateau de l'Assaladou, entre Sorgeat et d'Ignaux, au S-E d'Ax-les-Thermes en Ariège. Cette source primaire jusque-là inédite a été localisée par la présence d'anciens chantiers miniers à ciel ouvert. Repérés par des prospecteurs du BRGM et de la COGEMA à la fin des années 1970, ils ont été ensuite inventoriés (30 fosses), fouillés et datés par notre équipe entre 1993 et 1997, puis une étude minéralogique a été menée en 2000 et 2016. Deux groupes de travaux remarquables ont été étudiés : une fosse et un ensemble comprenant une mine à ciel ouvert prolongée par une galerie longue de 13 m. La fosse sondée a pu être datée des IIIe-IVe s. de notre ère grâce à une base de foyer conservée sur la sole. L'autre ensemble étudié (fosse et galerie) a confirmé cette datation avec la découverte de charbons de bois, résidus d'un abattage au feu et d'une céramique. Le plateau est constitué de schistes du Cambro-ordovicien, recoupés par des veines et des stockwerks de quartz. Le minerai suivi par ces travaux miniers comprend des lentilles de quartz dur, blanc à gris. Un grand nombre de failles ont recoupé le minerai et les roches encaissantes, facilitant l'abattage. L'or est visible à l'œil nu et se trouve dans le quartz en remplissage de cavités et il est aussi associé à l'arsénopyrite. Les mineurs antiques n'ont pas épuisé le gisement, laissant du minerai riche, accessible en surface. Ils semblent avoir fréquenté de façon saisonnière les lieux, tels des bergers (mineurs/paysans) exploitant un peu de minerai quand le plateau était déneigé., L'or dels Pirineus va ser conegut per escriptors antics i la recent investigació arqueològica i geològica l'han pogut detectar a l'altiplà d'Assaladou, entre Sorgeat i Ignaux, al sud-est d'Ax-les-Thermes a Ariège. Aquesta font primària prèviament inèdita ha estat localitzada per la presència d'antics punts de mines a cel obert. Identificat pels cercadors del BRGM i el COGEMA a finals de la dècada de 1970, van ser inventariats (30 fosses), excavats i datats pel nostre equip entre 1993 i 1997 i un estudi mineralògic es va dur a terme els anys 2000 i 2016. Es van estudiar dos zones de treballs notables: un fossat i un conjunt que inclou un fossat obert estès per una galeria de 13m de longitud. El pou que es va sondejar es va poder datar als segles III-IV de la nostra era gràcies a una base de llar preservada. L'altre conjunt estudiat (fossa i galeria) va confirmar aquesta datació amb el descobriment de carbó vegetal, residus d'incendis i ceràmica. L'altiplà està format per esquists Cambro-Ordovicians tallats per vetes i stockwerks de quars. El mineral obtingut d'aquestes obres mineres inclou lents de quars durs, de color blanc a gris. L'or és visible a simple vista i es troba en quars de rebliment de cavitats i també està associat amb l'arsenopirita. Els miners antics no van esgotar el dipòsit, deixant mineral ric, accessible a la superfície. Sembla que freqüentarien aquests punts de forma estacional, per exemple en el cas dels pastors (miners/camperols) explotant una mica de mineral quan a l'altiplà desapareixia la neu., Pyreneean gold was known by the Ancient authors and recent archaeo-geological research revealed it again in Asssaladou plateau located between Sorgeat and Ignaux villages, south-east of Ax-les-Thermes, Ariege, France. This source of primary gold was recently identified by the presence of Ancient mining workings at the surface. They were firstly observed by the exploration geologists of BRGM and COGEMA during late 1970'ies. Afterwards these mining vestiges were surveyed (30 pits), excavated and dated by our team during 1993-1997. A mineralogical study was carried out in 2000 and it was renewed in 2016. Two groups of mining workings were studied, a pit and an open pit continued underground by a 13 m long adit. The excavated pit was dated 3rd-4th c. AD on the basis of a fireplace. The study of the second mining complex (open pit and adit) confirmed the above mentioned dating on the basis of wood charcoal remnants of the fire setting and ceramics. The plateau is built up of Cambro-Ordovician schists, which are cut by quartz veins and stockworks. The ore is represented by white and grey quartz lenses affected by a dense faulting which facilitated the mining. Gold occurs as visible free gold hosted in voids within quartz and arsenopyrite. The Ancient miners did not exhaust the ore reserves, high-grade ore being still exposed at the surface. It seems that the mining works was seasonal and it was done by shepherds (miners/peasantries) during the periods without snow.

Somair, a subsidiary of AREVA, had over a period of years stockpiled low-grade ores from its Arlette, Ariege, Taza and Takriza uranium deposits in Niger. It had treated some of this material between 1972 and 1989 by heap leaching, though the recovery was low. In 2006 it again decided to treat the material by heap leaching and testwork was started on determining the optimum process conditions for an acid leach following agglomeration of the crushed ore. The results of the laboratory-scale testwork are presented, together with those based on 100 t samples. Commercial production started in 2009., Somair, a subsidiary of AREVA, had over a period of years stockpiled low-grade ores from its Arlette, Ariege, Taza and Takriza uranium deposits in Niger. It had treated some of this material between 1972 and 1989 by heap leaching, though the recovery was low. In 2006 it again decided to treat the material by heap leaching and testwork was started on determining the optimum process conditions for an acid leach following agglomeration of the crushed ore. The results of the laboratory-scale testwork are presented, together with those based on 100 t samples. Commercial production started in 2009.

info:eu-repo/semantics/nonPublished

info:eu-repo/semantics/nonPublished

The report presents an inventory of mineral deposits, within the Ariege region of France. Each deposit is described by its most precise and most commonly used name, with each entry including details of: access to the deposit; type of mineralisation in the area; and mineralogy and relative abundance of the ores observed. Precise geographic details (including Michelin map number and name and number of the 1:50 000 1GN map) are also included with each entry. An alphabetical classification by mineral is included at the end of the inventory., The report presents an inventory of mineral deposits, within the Ariege region of France. Each deposit is described by its most precise and most commonly used name, with each entry including details of: access to the deposit; type of mineralisation in the area; and mineralogy and relative abundance of the ores observed. Precise geographic details (including Michelin map number and name and number of the 1:50 000 1GN map) are also included with each entry. An alphabetical classification by mineral is included at the end of the inventory.

The use of the resistivity method in bauxite exploration of surface karsts in the Ariege Pyrenees is described. New equipment and a new method of analysis by computer modelling of the results have been developed. The objective was to optimise the siting of percussion drillholes for sampling and to determine the depth of bedrock. The trials were completely successful and enabled good assessment of the bauxite layer and its quality, Al2O3 content ranging from 25 to 40%., The use of the resistivity method in bauxite exploration of surface karsts in the Ariege Pyrenees is described. New equipment and a new method of analysis by computer modelling of the results have been developed. The objective was to optimise the siting of percussion drillholes for sampling and to determine the depth of bedrock. The trials were completely successful and enabled good assessment of the bauxite layer and its quality, Al2O3 content ranging from 25 to 40%.