A group of properties owned by Minera Cordillera del Viento is located in this area, including lead, barite and copper. The best known one is without a doubt the mine “Arroyo Nuevo“, important mantiform deposit of barite, which due to its thicknesses and high purity has been for a long time object of several studies and researches, as well as one of the main barite suppliers in the regional and national market for more than 30 years. An important fact is that before the discovery of this deposit and since the end of the nineteenth century and the first decade of the following century, this area was (together with Milla Michicó) epicenter of the gold mining in the north of Neuquén. Auriferous alluvions and a large quantity of veins concentrated most part of the mining activity in this district during the first years of 1900. Apparently, the alluvions with better performance were those exploited in the strings Milla Michicó, Nuevo, Cura Mallín, La Trasquila, Atrauquito and Manzano, in which in some cases average daily recoveries of 2 grams per miner were reported. (Stoll,1957).

Some years later, and with the alluvial deposits of the area partially depleted, the discovery of new veins in the zone of Huingancó and de las Minas hill in Andacollo moved and concentrated the auriferous exploitation in such spots, which was quite successful until the middle of 1957, when it started to decline.

Another fact worth remembering is that during the execution of the so-called Center Andean Plan (Plan Cordillerano Centro -1962-1968) the General Management of Fabricaciones Militares detected a group of geological evidences correspondent to disseminated mineralization of copper in the area Los Maitenes–El Salvaje, only about 4 km to the north of Cura Maillín. Therefore, Fabricaciones Militares established there the mining reservation area Nº 55, with and estimated surface of 52 km², and started exploration works orientated to the search of a deposit with those characteristics. Even when the mentioned explorations did not help back then to define the limits of the deposit, they confirmed the presence of the disseminated mineralization and the geological information obtained was a useful guide for many companies that later on performed new exploration works in different sites of the district. In some cases, new prospective goals or important evidences of new mineralizations were detected, both vetiform and disseminated and especially of gold and silver

The district Andacollo was included and the zone Arroyo Nuevo was established as an area of interest in one of the last reviews in charge of the technical Japanese mission JICA and the National Mining Undersecretary about the state of situation of mining areas and prospects of interest in order to promote and develop them in the Patagonia (JICA, S,M.N, 2000).

In the mentioned report the area is considered as a high potential zone, reason why the Japanese mission suggested not including it for a second phase of complementary studies in order to confirm such condition. “In this disctrict mining activities by private companies is on-going and high potenciality has been already proven.. With consideration given to the purpose of this survey that new promising areas should be extracted, it si judged that this district is not necessary to be included in the Phase 2 survey“. (pp 251. JICA,SMN,2000).

The following mineralizations located in the surroundings of the properties owned by Minera Cordillera del Viento in the area of Cura Mallín are important due to their prospective interest:

Los Maitenes – El Salvaje
Vein Paulo Nicolás
Deposit Arroyo Nuevo
Prospect disseminated gold Arroyo Nuevo
Veins de la Primavera
Veins Basilio and Los Mellizos
Veins and disseminations of Yeguas Hill.

Los Maitenes - El Salvaje This is a disseminated mineralization of copper porphyry with hydrothermal alteration development of the classic type Lowell and Gilbert (1980). (in Casé and Danieli, 1997). It presents evidence of two intrusive cycles, relating the mineralization of pyrite, chalcopyrite, some molybdenite, magnetite and rutile with the last magmatic event of the Eocene age. The homogenization temperatures range between 320° and 370° C with boiling phases of up to 400°C for salinities of 26% in NaCl weight. (Domínguez et al,1984).

Present hydrothermal alteration: potassium, phyllic propylitic and silication in small veins. Vein Paulo Nicolás This vein is located in a breccia between two parallel faults in volcanites of the group Choiyoi. Consists in galena, sphalerite, pyrite chalcopyrite, tennantite - tetrahedrite, and gold in quartz veinstone and calcite. The texture is of crustifyed filling and well developed tape. Formed by low salinity fluids with presence of CO2, homogenization temperatures of 330°C and a location depth of 800 m.

Hydro-thermal alteration: quartz sericite, intermediate argillic, propylitic and late carbonization. (Domínguez y Garrido, 1982). Deposit Arroyo Nuevo This is a barite mantle consistent with shales of the formation called Los Molles. Related with a fault structure , there is a breccia with lutite clastics and clayey matrix, a vein/sill of dacitic porphyry, sandstone of fine particles with intercalations of conglomerated sandstone and andesite dykes, forming two dominant systems in the directions N-S and E-W. The mineralization is barite with calcite, pyrite, quartz, arsenopyrite greigite, galena and iron oxides.

Hydrothermal alteration: Quartz sericite, silication, chlorite and moderate to intense clayey.

The mine, today inactive, has more than 12.000 m of underground mining works developed in rooms and pillars in different areas of the exploitation, called La Vieja, Bellotti and Fuentes 1, 3 and 5. Prospect disseminated gold Arroyo Nuevo Placer Dome executed exploration works in the area of Arroyo Nuevo, in the southern part of the district Andacollo, between the years 1993 and 1995. During those works, geochemical sampling of current sediments and ditches were done for survey of rocks in chutes. Even when the geological evidences showed the possible existence of some disseminated deposits of Cu-Au, Placer abandoned the exploration works apparently due to the reduced volume and low law detected in the explored areas.

During the year 1994 Minera Andes S.A. made an assessment of the antecedents of prospect Arroyo Nuevo and focused the explorations around the mines of barite of Cura Maillín. The exploration program included mapping of the area in a scale 1:1250 and sampling of rocks and soils on areas with jasperoide in carbonate rocks. In relation to the soils samples MASA (1997) reports strong anomalies of Au, Ag, Zn and As, while some samples of the area with jasperoides contained gold values of 3 to 9 g/t. The exploration was extended in 1997 with more detailed works during which an area of 37 km² was covered. Then, by means of soil geochemistry, induced polarization and magnetometry an area of 9 km² was selected, with important anomalies of gold and mercury in soil and rocks as well as intense silication both in the mesozoic sedimentites and in younger intrusives. MASA made 27 reverse air drillings, summing up 1220 meters, cutting mineralized levels inside sedimentites of up to 5 feet thick with contents of more than 3.5 grams of gold per ton, 8% Pb and 1% Zn. Viens de La Primavera They are gold sulfide veins, formed by pyrite, pyrrotite, sphalerite, galena, chalcopyrite, magnetite, specularite, rutile, anatase, gold and electro, bornite, enargite, covelline, bismuth sulfosalts, in quartz veinstone and calcite. The main textures are filling of open spaces and have areal zonation. They consist in filling of faults in rocks of the group Choiyoi, with general directions E-W and dips variable between 65º and 75º. The megascopic textures of the initial quartz and pyrite deposits are of crustifyed filling in all the veins. Hydrothermal alteration: quartz-sericite, intermediate and propilitic argillyte and kaolinitization in the vein Colorada. Veins Basilio and Los Mellizo These are veins of copper, lead, silver and zinc, developed in fractures in mesozoic sedimentites, to the south-east and south respectively of Cura Mallín. The mineralization consists in chalcopyrite, with subordinated amounts of chalcosite, covelline, bornite, galena, spharalite in quartz veinstone, calcite and barite. The oxidized ores are malachite and azurite and less frequent cuprite, limonite and native copper. Veins and disseminations of Yeguas hill. Its main properties were detailed in the first title correspondent to this subject.
According to the assessment done by Danderfer (2006), the area where are currently located several properties owned by Minera Cordillera del Viento could be described as “an area of great importance for the exploration of metals” (Ag-Au-Pb-Zn).

After such definitions, Minera Cordillera del Viento S.A., presented to the Province Mining Authority a proposal of exploratory works for the mines in these areas.

Such works are summarized in the working plan designed by Casé (2007), which proposed to define new explorations within the limits of the properties of the mines called “Raza Fuerte“ and “Don Carlo“. The suggestion of focusing the exploration in the mentioned deposits is based on the fact that both properties, apart from presenting favorable geological and structural conditions, are virtually surrounded by the explorations made by MAGSA. The mentioned working plan, includes the following important observations:
“The area occupied by the properties of both mines corresponds to the southern sector of the stratabound barite deposit Arroyo Nuevo. It is a fault area in which at least two important fractures meet, which limit the barite mineralization and at the same time they are associated to the intrusion of stocks in dacitic veins. When the mine Arroyo Nuevo was exploited, the sector was object of permanent exploration in order to detect the continuity of the barite mantle, both from the outside and inside of the mine, with not very promising results in most cases. Probably those results of greater interests were the ones obtained by Minera Andes, apparently intersecting horizons with some disseminated mineralization of gold in sediments. The isolated encounters of barite, both in Raza Fuerte and Don Carlos, do not rule out the possibility of finding other barite mineralizations in the sector.

In agreement with the results of the petrocalcographic report and to the geological and structural conditions, the area of the mines Raza Fuerte and Don Carlos could correspond to an important fracture area that favored the circulation of hydrothermal fluids. Barite and basic metals deposits could be associated to this fact, as well as the presence of gold and other metallic elements. The area of most prospective interest is located between two regional fractures to the south of the mine Arroyo Nuevo, indicated in the attached map as FS1 and FS2. The later seems to correspond with the main area of delivery and circulation of hydrothermal fluids responsible for the formation of breccias and silica porous bodies (silica vuggy).

The area of both deposits has prospective interest since the analyzed rocks could correspond in a first approximation to a favorable environment for the formation of sub-volcanic deposits of gold and basic metals associated to barite.

Taking this fact into account, it is considered that the exploration of the area must continue with a more detailed mapping focused in the described area, geochemical sampling and survey of present structures and alterations.“

The sampling done by Danderfer (2006) shows that the silication sectors with presence of sulfides could be extended to the north of the selected by Casé (2007), which could expand the prospective possibilities of the site. Considering the limited amount of samples available to evaluate the potential of the area covered by the properties owned by Minera Cordillera del Viento (which all together sum up approximately 900 hectares), the works proposed in both reports would contribute to define the most interesting sites to do further explorations.

The situation of this area is quite similar to the situation in Yeguas hill, with the significant difference that a larger legal covering of the properties of Minera Cordillera del Viento in the area grants better possibilities to place within them new exploratory works and surveys without interfering with the existing mining rights in the environment.
Casé, A.M, 2007. Exploration program of mines Raza Fuerte Expte Nº 13187/88 and Don Carlos Expte Nº 4357/67, Mines Department. Report on works correspondent to the first stage. National Mining Direction. (unpublished).

Casé A.M., and Danieli JC.,1997. Prospective possibilities in the southern area of the reservation Andacollo. Provincial Mining Direction. Zapala, Province of Neuquén. (unpublished).

Danderfer J.C., 2006. Minera Cordillera del Viento S.A. Geological summary of mining properties studied on December 2005- May 2006. (unpublished)

Domínguez, E.A. and Garrido, M.E.,1982. The vertical variation of sub-volcanic plumbo-zinciferous mineralization in La Primavera, Andacollo, Province of Neuquén, Argentina. V Geology Latin-American Congress. Argentina. II. 679-697.

Domínguez E.,A., Aliotta G., Garrido M., Danieli, J.C:, Ronconi N., Casé A.M., and Palacios, M. 1984. Los Maitenes- El Salvaje a hydrothermal system of phorphyryc type. IX Geological Argentine Congress. VII .443-458. Bariloche. INFOMINE 20 November 1997. Minera Andes Incorporated. www.minandes.com

JICA 2000- Report on Regional Survey for Mineral Resources in the Southern Andes Area -The Argentine Republic. Phase I Japan International Cooperation Agency- Metal Mining Agency of Japan. National Mining Undersecretay. Buenos Aires.

Plan Cordillerano Centro. DGFM 1969 Report on the area of Cura Mallín. Plan Cordillerano Centro-Neuquén final reports. General Management of Fabricaciones Militares and Province of Neuquén. Argentina-Mendoza.

Stoll, W.C., 1957. Geology and Mineral Deposits in Andacollo, Province of Neuquén National Mining Direction. National Ministry of Commerce and Industry. Annals VI. Buenos Aires.

Yeguas Hill Area

Structure and mineralization of the main veins.
Hydrothermal alteration and geochemical features of the rocks in the area.
Mine “Desconfianza“. Possibilities of exploration in its area of influence.

More information

Copper-molybdenum, gold and base metals

Cerro del Diablo Area
Loncopué Area
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Prospectos metales metalíferos


Potassium, asphaltites and biogenetic sulfur.