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80-559: Minas da Panasqueira or Mina da Panasqueira (English: 'Panasqueira mine') is the generic name for a set of mining operations between Cabeço do Pião ( Fundão municipality) and the village of Panasqueira ( Covilhã municipality), which has operated in a technically integrated and continuous manner practically since the discovery of ore there. Subsequently, it was agglomerated into a single administrative entity called Couto Mineiro da Panasqueira (English: 'Panasqueira Mining Reserve') which had its last demarcation on 9 March 1971 and later on in

160-484: A 5.1 km long aerial cable. The statements of 1912 are representative of a typical year of that time and indicate an annual production of 277 t of concentrates with 65% WO 3 , 1,078 m of galleries and a total of 244 workers. With the beginning of the First World War and the consequent increase in the price of wolfram, there was an increase in concentrate production which stabilized during this period at

240-504: A centimeter to meter scale) and random occurrence. The reason for the quality and perfection of the crystals is the high amount of volatile elements present in Panasqueira's veins, which allows the cavities to form under suitable temperature and pressure conditions. As an initiative of the parish council of the Village of Saint Francis de Assisi  [ pt ] , and in collaboration with

320-419: A corresponding period of expansion. However, soon afterwards prices suddenly dropped again. During this period the production was stockpiled rather than sold below production price, but due to financial expenses it was decided to increase capital with the entry of new shareholders. The company adopted a new name in 1973 with the acquisition of 20% of its capital by BNU ( Banco Nacional Ultramarino ). In 1974 when

400-559: A dense series of thin lentils of marine origin, of clay and sandstone, which later underwent low-grade regional metamorphism (a facies of greenschist ) during the initial compressive phases of the Variscan orogeny . The mines are located in the area of the greywacke schist complex in the ZCI. It is a region where metamorphosed sedimentary rock predominates, but where a large number of acidic and basic eruptive manifestations also occur. The age of

480-498: A deposit recovery of 84%. Currently all stope work is mechanized and the stoping sequence proceeds in five phases: For decades there were three independent processing plants which later complemented each other, Panasqueira, Cabeço do Pião and Barroca Grande. Panasqueira Plant began to be built in the 19th century and was progressively transferred, from 1928, to Barroca Grande which has a more central location, more available area, greater access to water and other advantages that led to

560-405: A shiny black stone and took it to Manuel dos Santos, in the parish of Barroca do Zêzere. After visiting the site, dos Santos went to Lisbon and asked Professor of Mineralogy and engineer Silva Pinto to examine the place where the sample had been discovered. On his return, dos Santos bought the land and began to mine for wolfram. The mining was done in an artisanal manner and supplemented by ore that

640-484: A shipping record dated 25 November 1909 which indicated 41 tons of wolfram concentrates; a notable amount for a mine of the time. On 15 July 1911, a sale deed to the Wolfram Mining and Smelting Company Limited for 11 concessions and 125 ha of land was signed. The company's tenure was a time of great development with the opening of many galleries, expansion and modernization of the washing plants, and installation of

720-679: A value close to 30 t per month. The number of direct employees of the company stood at 800, plus around 200 self-employed workers. At the end of the First World War (1918–1919) there was a drop in prices, production was paralysed, leaving the workforce reduced to 100 workers employed in accessory jobs. From 1920 to 1923 there was a period of intense mining, followed by a near stoppage in 1923, reactivation in 1924 and near complete paralysation in 1926. At this time tin mining began, first in Fontes Casinhas and later elsewhere. In 1928 with

800-467: A vertical shaft was installed in 1996, which brings the ore up to level 2 (at 560 m elevation). The ore is extracted in stopes by drilling and blasting with explosives , and loaded by LHDs into storage and extraction bins which are regularly arranged and fill 4 ton minecarts . The minecarts circulate between levels 2 and 3, dumping the ore into the crushing chamber on level 2. The minecarts are pulled by battery or diesel locomotives. The large size of

880-510: A very rudimentary manual washing plant employing almost 100 people. At a later date, the concession was sold to the banker Henrique Burnay, 1st Earl of Burnay. The mine increased in size with the preparation of veins and expansion of surface facilities. In 1901 the concession was leased to an English company for a short period. Subsequently, the first mechanical steam-operated washing machine was assembled. The first galleries (numbers 10 and 13) date from this time. There are no production records but

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960-478: Is amphibolitized . They do not affect mineralization and are intersected by the vein system. These dikes follow the two deformation phases. In the eastern zone of the mining concession there are mottled schists with spots of biotite and chlorite, and less frequently chiastolite and cordierite which correspond to a contact metamorphism halo, which is considered to indicate the presence of an intrusion of an in-depth magmatic body. The sub-horizontal layout of

1040-401: Is a light yellow crystalline solid. Tungsten(VI) oxide occurs naturally in the form of hydrates , which include minerals: tungstite WO 3 ·H 2 O, meymacite WO 3 ·2H 2 O and hydrotungstite (of the same composition as meymacite, however sometimes written as H 2 WO 4 ). These minerals are rare to very rare secondary tungsten minerals. In 1841, a chemist named Robert Oxland gave

1120-528: Is a quartz of exudation, sterile, and a product of the segregation and recrystallization of quartz by regional metamorphism. They are prior to mineralized veins and often form 90º angles. Establishing a deposition sequence for the minerals from the mine is quite difficult due to the existence of different stages of formation and the fact that some of them only appear in certain areas of the mining concession, making their correlation very difficult. However, Kelly & Rye (1979) defined four stages of deposition for

1200-487: Is also bottled from several sources in the municipality of Fundão. The Cavleiro tree is a common trade item from this region. It is used in everyday products such as wooden dolls, shoes and bedposts. WO3 Tungsten(VI) oxide , also known as tungsten trioxide is a chemical compound of oxygen and the transition metal tungsten , with formula WO 3 . The compound is also called tungstic anhydride , reflecting its relation to tungstic acid H 2 WO 4 . It

1280-483: Is also known worldwide in the tungsten (wolfram) industry, not only for its quality and volume of production, duration and adaptability of operation; but also due to the maturity of the technical solutions both underground and in ore processing. Minas da Panasqueira is named after the location of the initial mining operation. At the end of the 19th century, the area was covered with gorse , broom bush and several species of low-lying bushes and pines. The stony ground

1360-434: Is extensive and follows the location of Variscan granite outcrops, in addition to alignments parallel to the outcrops, and are generally found in halos of contact metamorphism reflecting the presence of granites at shallow depths (at Panasqueira, Argemela, Gois, Borralha, Vale das Gatas, Ribeira, and Argozelo, among others). Mineralization occurs both in the contact zone of intrusive granites and metasediments , and in

1440-465: Is intimately related to that of its originally Jewish , then New Christian or Marrano , population. Although the place was already mentioned in documents from 1307 referring 32 houses, the bulk of the population only settled after the 1492 Expulsion of the Jews from Spain by Ferdinand and Isabella , mainly Spanish Jews ( sephardic ). Close to the border, and already home to significant Jewish minorities

1520-518: Is monoclinic with space group P2 1 /n. The pure compound is an electric insulator, but oxygen-deficient varieties, such as WO 2.90 = W 20 O 58 , are dark blue to purple in color and conduct electricity. They can be prepared by combining the trioxide and the dioxide WO 2 at 1000 °C in vacuum. Possible signs of superconductivity with critical temperatures T c = 80–90 K were claimed in sodium-doped and oxygen-deficient WO 3 crystals. If confirmed, these would be

1600-454: Is sold as inert material for the civil construction. Since 1985, the mine has been the only wolfram mine in Portugal , and from 1950 until the end of 2016, it was responsible for 77% of the country's total wolfram production. The main commercialized product, wolfram concentrates (wolframite in the case of Panasqueira) are a reference in the industry as they have had the highest grade and purity in

1680-514: Is wolfram (wolframite); tin (cassiterite) and copper ( chalcopyrite ) are mining by-products. In addition to these minerals, there is a great variety of other minerals such as: muscovite , topaz , fluorite , arsenopyrite , pyrite , pyrrhotite , marcasite , sphalerite , apatite , siderite , calcite and dolomite . There is also a very typical morphology in these veins called rabo de enguia (English: 'eel's tail'). This morphology consists of pressure-induced throttling, often resulting in

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1760-577: The Natural History Museum in London . Panasqueira is located in the municipality of Covilhã, Castelo Branco District between the mountain ranges of Serra do Açor  [ pt ] and Gardunha . The mining concession is called the "C-18 Mining Concession" and has an area of 1,913   ha. The lowest point of the concession is located along the Zêzere River at an elevation of 360   m and

1840-726: The Prime-Minister of Portugal, legal restraints on the New Christians were abolished and rights equiparated to those of the Old Christians . Pombal tried to recreate the industrial preëminence of Fundão by founding the Royal Factories (today known as the City Hall ). These efforts allowed a measure of revival to the wool industries of the city, and cloth was again exported to northern Europe . The city decayed again after its sack during

1920-581: The Romans , there was a Celtic Lusitanian Castro or fortified village in nearby São Brás Mount. The remains of a villa or agricultural manor house , workers houses and other associated buildings from the time of the Roman Empire have been found in the underground of the centre of the current city. This villa was rebuilt as a fortified medieval mansion during the High Middle Ages . The history of Fundão

2000-481: The ore mining work began and the first washing plant was built. The name of this valley derives from panasco , the common name given to various types of grass ( Dactylis , Agrostis ) very common in the region, especially in fields where rye was sown. The population called this new mine Minas da Panasqueira . There are records of extensive galleries in Vale da Ermida, Fontes Casinhas and Courelas associated with

2080-421: The 1950s the longwall method was widespread throughout the mine. Depending on the inclination of the veins, parallel fronts (for sub-horizontal veins) or irregular fronts, also known in the mine as modas e bordados (English: 'fashions and embroidery'; for veins with an inclination between 7º and 12º), were used. Within the stope, manually filled wooden minecarts circulated that transported the disassembled ore to

2160-845: The Cebola and 8E faults belong to the second. It is thought that the latter were initiated with strike-slip movements during the Variscan orogeny and reactivated during the Alpine orogeny . It is a complex of faults in the left shear zone, which affects the Ordovician formations of the Serra do Vidual in the southwest, and joins with the Manteigas –Unhais da Serra fault in the northeast. There are no recognized outcrops of mineralized veins north-northwest of this accident , neither of wolframite nor cassiterite. Mining at Panasqueira has always been done by underground methods, with

2240-582: The Cova da Beira region, the region received many refugees. They settled in the community of Fundão, which their numbers swelled to that of a city. The influx of Jewish artisans and merchants quickly transformed it into an important commercial and industrial center. With the establishment of the Portuguese Inquisition shortly thereafter, many Jews and New Christians were arrested, tortured, executed or had their possessions expropriated. The commercial dynamism of

2320-477: The Panasqueira plant being completely deactivated in the 1960s. The Cabeço do Pião plant, like the one at Panasqueira, began to be built at the end of the 19th century. With the abandonment of this vein exploitation zone, and due to the greater availability of water from the Zêzere River, this plant only treated the pre-concentrates that came first by aerial cable and later by truck from the Barroca Grande plant. At

2400-463: The abundance of mineral paragenesis . The wolfram-tin-copper mineralized zone consists of sub-horizontal quartz dikes (usually with an inclination of less than 25º, increasing to 30–40º near the greisen dome) that overlap and fill in fractures mainly developed in schist rocks, with an average depth of 25 cm (ranging from 1 to 150 cm) and a width that can reach 200 m, with an average of 48 m. The most important mineral in economical terms

2480-413: The acquisition in 1974 of a raise borer , the spacing between levels (level 3) increased to 90 m. There is a mine drainage level (level 530), 30 m below level 2 where historically ore was also extracted. All mine drainage exits through this gallery. Water from higher levels flows by gravity, while water below the drainage level is sent to a pumping station installed below level 3. Horizontally,

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2560-474: The activity in the three main mining areas of the concession (Panasqueira, Barroca Grande and Rio). This cycle associated with the Second World War was notable with 750 workers in 1934; 4,457 in 1942 and 10,540 workers in 1943. The plant at Rio reached a capacity of 300 t per day and that of Panasqueira 1,000 t per day. The monthly production of concentrates reached 300 t at that time, more than

2640-498: The central and northern region of Portugal where the vein deposits are of greatest economic importance. The ZGMTM and ZCI differ essentially by the occurrence of allochthonous and para- authochthonous thrust sheets in the ZGMTM. Most of the outcropping rocks are granites and schists of the greywacke schist complex. To a lesser extent Precambrian , Ordovician and Silurian rocks occur. The distribution of tin and wolfram deposits

2720-477: The city was affected. The place was proclaimed a city in 1580 by its notables, after support for their attempt was declared by Dom António, Prior do Crato , to preserve Portuguese independence against the ambitions of King Philip II of Spain (Philip I of Portugal). The Municipal Council and autonomy were granted in 1747. During the Enlightenment of the late 18th century, under the rule of Marquis of Pombal ,

2800-429: The company changed its name to Sojitz Beralt Tin and Wolfram Portugal. Mining was done in a very large area of the mine, returning to previously abandoned levels, i.e. levels 1 and 0. Prospecting was carried out to identify additional reserves within and surrounding the mining concession. Tailings from the old Panasqueira village washing plant that contained interesting levels of wolfram were also mined. In 2008, part of

2880-444: The company with the introduction of scrapers and mechanical loaders. Mules were replaced by locomotives. Cassiterite production was increased to compensate for low wolfram prices. The production of copper concentrates began in 1962. From 1957 to 1965 there was a further decrease in the price of wolfram which resulted in a reduction of production in order to control costs. In 1966, a positive price trend began that peaked in 1970 with

2960-579: The concession that was located south of the Zêzere River was detached, leaving the management of the old infrastructure in the hands of the Fundão city council, although the mining company maintained responsibility for monitoring the water in the Zêzere and the control of acid runoff. Almonty Industries is the current owner of the mine, acquiring it on 6 January 2016 and once again changing the name to Beralt Tin and Wolfram. During this period mining continued throughout

3040-520: The conditions for closing the mine (a maintenance period for the two water treatment plants at the mine and a water quality monitoring program in the Bodelhão stream and Zêzere River ), Minorco decided to sell the company to Avocet Mining . Major changes took place during the initial period of Avocet, namely the reopening of the mine in January 1994, the transfer of the washing plant from Rio to Barroca Grande,

3120-458: The contact zone of intrusive granites in other older granites. The main occurrences of wolfram and tin are conditioned by structures inherited from early and late Variscan shears or fractures related to the installation of post-tectonic granites. Contact occurs between the greywacke schist complex of the Beiras group and the Variscan granite complex of northern Portugal. The Beiras group is formed by

3200-426: The continuation of the opening of level 3 and the construction of an extraction shaft between levels 2 and 3, which began operating in 1998. The final period of Avocet's management was of major economical difficulty due to the extremely low and persistent wolfram prices with a degradation of the mine's production capacity which, coupled with the termination on 31 December 2003 of contracts with customers that guaranteed

3280-538: The defeated Napoleonic French invasions of Portugal, and the subsequent Civil War between supporters of the Liberal Constitutionalist D. Pedro and his brother Conservative Absolutist D. Miguel , who were competing for the throne. The film festival IMAGO – Young Film and Video Festival was organized in Fundão from 1999 to 2009. Fundão has a Mediterranean climate ( Köppen : Csa ) with cool, rainy winters and hot, dry summers. Administratively,

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3360-488: The end of the 1980s, the Panasqueira mine was large enough that its drainage water was sufficient to supply the necessary flow to the entire industrial structure; thus between 1992 and 1996, in order to rationalize costs and due to environmental reasons all ore concentration operations were centralized at the Barroca Grande plant. Fund%C3%A3o, Portugal During the Iron Age , from about 1000 B.C. until its destruction by

3440-467: The entry of new shareholders, the name was changed and important work began, such as a new aerial cableway and a large washing plant in Rio (Cabeço do Pião). Production returned to values close to 30 t of concentrate per month, until another production stoppage period from 1931 to 1934. At this time a tin smelting furnace was installed in Rio. In 1934 there was an increase in wolfram prices and consequent growth of

3520-472: The exception of a small mixed method tin mine ( glory hole ) in Vale de Ermida in the 1950s. The mine galleries are horizontal and since the joining of the two main historical mining areas (Panasqueira and Barroca Grande) with the main gallery of Barroca Grande; it was renamed level 0. Later level 1 was traced and then levels 2 and 3. The spacing between these levels is 60 m as previously the opening systems for chimneys (raises) were complex and dangerous. With

3600-505: The exploitation of tin , but this period is poorly documented. There are records of alluvial exploitation of tin in the area of São Jorge da Beira, which is attributed to the Roman period. At the end of the 19th century, the region was covered with thick heather scrub, broom, arbutus and pine trees, which were used in the production of charcoal for sale in Fundão and Covilhã. One of these charcoal burners, known as "O Pescão de Casegas", found

3680-527: The first procedures for preparing tungsten trioxide and sodium tungstate . He was granted patents for his work soon after, and is considered to be the founder of systematic tungsten chemistry. The crystal structure of tungsten trioxide is temperature dependent. It is tetragonal at temperatures above 740 °C, orthorhombic from 330 to 740 °C, monoclinic from 17 to 330 °C, triclinic from −50 to 17 °C, and monoclinic again at temperatures below −50 °C. The most common structure of WO 3

3760-521: The first superconducting materials containing no copper, with T c higher than the boiling point of liquid nitrogen at normal pressure. Tungsten trioxide is obtained as an intermediate in the recovery of tungsten from its minerals. Tungsten ores can be treated with alkalis to produce soluble tungstates . Alternatively, CaWO 4 , or scheelite , is allowed to react with HCl to produce tungstic acid , which decomposes to WO 3 and water at high temperatures. Another common way to synthesize WO 3

3840-497: The galleries of the various levels form a grid in which the north–south galleries are called panels and the east–west galleries are called drives . Extraction of ore to the surface was done by tunnels above level 0 and then through several vertical shafts . With the relocation of the production zones to the southwest of the washing plant, in order to reduce the operational complexity of the various extraction shafts, increase capacity and centralize extraction by modern means closer to

3920-567: The highest at the geographic landmark of Chiqueiro at 1,086   m. The landscape is covered with extensive eucalyptus and maritime pine plantations with small terraces planted with olive trees, vines, and some fruit trees. The mine is the largest local employer with approximately 300 direct workers, who reside mainly in the surrounding villages, including Barroca Grande, São Jorge da Beira  [ pt ] , Silvares (Fundão)  [ pt ] , Unhais-o-Velho  [ pt ] and Dornelas do Zêzere  [ pt ] . Regarding

4000-454: The horizontal. A different and relatively frequent structure in both the mine and the surrounding area are quartz structures called seixo bravo (English: 'wild pebbles'). This connotation is mainly due to their hardness and the fact that they do not contain useful minerals. These are lenticular, irregular veins, with a sub-vertical inclination whose arrangement is consistent with the main schistosity and can easily reach 3 m in width. It

4080-752: The labour used in stoping. The importance of investigating another support system that would at the same time allow greater mechanization of the remaining stoping operations resulted in the transition to the room and pillar method . The pillars were successively reduced in size, and for the final phase of stoping two support methods were tested: reinforced concrete columns formed by overlapping tiles, and piles of wood stacked in various ways. The concrete columns were abandoned almost immediately due to their cost and lack of elasticity that led to sudden breaks. The wooden piles gave better results and were implemented first in combination with stone walls and then alone. The room and pillar method allowed an increasing mechanization of

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4160-480: The loss of a large part of the finer fraction of the ore when it was violently projected against the stone walls. The method evolved in order to find solutions for the loss of this finer and consequently more mineralized fraction. The year 1958 marked a fundamental evolution in the longwall mining method, due to a lack of manpower caused by immigration. Mechanization was necessary with the adaptation of haulers or scrapers that had high capacity, versatility and range. For

4240-556: The metasediments is attributed to the Cambrian or Upper Precambrian. There are basic intrusive rocks identified as dolerites which occur as 0.5 to 3   m thick veins, mainly oriented north to south and vertically inclined. They are dark grey, fine grained and micro- porphyritic , being altered in contact with the mineral veins. They present irregular fractures and polyhedral disjunction. Mineralogically they essentially consist of labradorite , hornblende , chlorite and pyroxene which

4320-816: The mine at the National Museum of Natural History and Science in Lisbon  [ pt ] . There are mineral collections from the mine in other museums in Portugal such as the National Laboratory of Energy and Geology (LNEG) in São Mamede de Infesta . Many of the best museums worldwide with mineral collections have Panasqueira specimens. Good examples can be seen at the American Museum of Natural History in New York or at

4400-422: The mine between levels 0 and 3, resuming mining in an old tin-rich area in the northern zone of level 2, known as Panasqueira Deep. The possibility of recovering various metals contained in sludge dams, especially wolfram, tin and copper, is being studied at the moment. There are no reliable records of mining production between 1898 and 1933; however it is known, that it was relevant in some years of this period. In

4480-447: The mine, namely panasqueiraite and thadeuite. Several mineral collections around the world include specimens from the mine, especially the ferberite and fluorapatite varieties of wolframite. The collection of collectible-quality mineral samples is done daily, whenever possible, and as the underground mine work progresses. Most of the samples are found in cavities in the veins, which in mining slang are called rotos , of variable size (on

4560-507: The mineralogy of the veins: From a structural point of view, the mine region is characterized by the occurrence of a large number of faults and fractures, locally well marked, both in the type of filling they have and in their orientation. There are two major fault systems: those belonging to the north–south system and those belonging to the NE-SW to ENE-WSW system. To the first belong the main, 3W, 1W, Fonte da Lameiras, and Vale das Freiras faults;

4640-402: The mining company, several spaces related to the mine have been turned into a museum, where photos and other objects related to the mine's history can be viewed. There is an old deactivated diesel tank that has been transformed into a 3-story building in the shape of a gasometer and which contains various exhibition spaces. Since 2006 there has been a set of rooms with a permanent exhibition of

4720-564: The most important wolframite mines in the world (a mineral source for the element tungsten ) are explored within its municipal limits. Other important mines extract lead and tin . The Panasqueira is the generic name for a set of mining operations between Cabeço do Pião in Fundão Municipality and the village of Panasqueira in the neighboring municipality of Covilhã , which operated in a technically integrated manner and continue practically since its discovery. High quality mineral water

4800-611: The municipality is divided into 23 civil parishes ( freguesias ): The town is an important local center of industry and services. Around it lies some of the most fertile land in the region, in a large valley ( Cova da Beira ) between the Gardunha and Estrela ranges, where the Zêzere River starts its way towards the Tagus . The most significant productions are cherries , peaches , olive oil , wine , wood pulp and vegetables . Some of

4880-399: The new centre of the mining area, an underground crushing chamber was installed at 530 m elevation. A 17º incline conveyor belt transports the crushed ore to several surface storage pits that feed the washing plant and allow the necessary flexibility between the mine and the plant. This system, which began operation in 1981 is still in use today. For ore extraction below level 2 (level 3)

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4960-399: The next phase, when the pressure of the ascending magma and the resistance of the host rock to intrusion are equal, there is a decrease in fluid pressure and consequently the future ore body is sheared and further fractured. The fluids turn the interior of the granite dome into greisen . Finally, the massif enters a solidification phase and, due to cooling, the topmost zone contracts. This is

5040-779: The occurrence of wolfram and tin deposits in Portugal, the Iberian tin-wolfram metallogenic province extends east of the Porto-Coimbra-Tomar shear and northeast of the Juromenha thrust . With the exception of the deposits linked to the granite of St. Eulália in the Ossa Morena Zone , the remainder are located in the Central Iberian Zone (ZCI), Galicia-Trás-os-Montes Zone (ZGMTM) and West Asturian Leonese Zone . The Portuguese tin-wolfram metallogenic province develops throughout

5120-422: The period that is recorded (1934 to present), 128,110 t of wolfram concentrates, 6,576 t of tin concentrates and 32,410 t of copper concentrates were produced. The wolfram concentrates produced have an average of 75% WO 3 , the tin concentrates an average of 74% tin, and the copper concentrates an average of 28–30% copper. Along with these main products, minerals for collecting are also extracted and gravel

5200-416: The pits where it dropped by gravity to the lower rolling level. Mechanical drilling was done with jackhammers and the start-up was done, as today, with explosives. When filling the minecarts the overburden was chosen to remain as a wall that accompanied the progress of the excavation, forming the structure responsible for supporting the cavity. This method had several drawbacks such as a high labour demand and

5280-429: The precipitation of wolframite and cassiterite at the ends. They regularly display a structure that suggests different filling phases related to reopening events. The veins with the greatest inclination (30º to 40º), found in the vicinity of the greisen dome, are called "galo" veins. Usually these types of veins are also well mineralized. They sometimes show variable deviations of 1 to 5 m, and after dipping return to

5360-501: The present C-18 Mining Concession (16 December 1992). The mining facilities are currently centralized in the area of Barroca Grande – Aldeia de São Francisco de Assis (Covilhã) through which the current underground operation, ore extraction and processing facilities are accessed. The mine has been operating nearly without interruption since 1901, with a strong impact on the identity, history and current society of Beira Interior in general and Cova da Beira in particular. It

5440-472: The price became more favorable the stockpile at the mine was sold. From 1974 onwards, there was a considerable increase in labour costs which accelerated of the mechanization of underground operations. During the 1970s various alternatives for deepening the mine were studied, and level 2 was opened and extraction was carried out through an inclined shaft that began operation in 1982. From 1983 the price began to fall again and Charter Consolidated , holder of 80% of

5520-523: The recovery and acquisition of the mine by Almonty. From May 2004 to October 2007 the American group Almonty managed the mines through its representative Primary Metals. During this period the productive capacity of the mines was restored and production on level 2 was resumed. The Japanese company Sojitz Corporation acquired the mine in October 2007 and sold it back to Almonty in January 2016. During this period

5600-529: The rest of the country combined. At that time the underground connection from Barroca Grande to Panasqueira took place. During the Second World War, Panasqueira was the largest mine in the country and one of the largest wolfram mines in the world. The price of wolfram dropped dramatically at the end of the war, only rising again in 1950 due to the Korean War . During this period there was a great modernization of

5680-612: The sale of production at a price above the market value, led the company to notify the General Directorate of Mines of its intention to close the mine as of 1 January 2004. Following negotiations, and based on well-founded expectations that within six months there would be an increase in prices, the State guaranteed the payment of workers' wages between March and August 2004 through the Wage Guarantee Fund, which created conditions for

5760-419: The shares, sold its stake to Minorco in 1990. In 1993, due to several years of low wolfram prices, Minorco asked the General Directorate of Mines to close the mine, having submitted a request for authorization to sell the washing plant as scrap metal and to disconnect the sewage on level 3. Due to the reply from the General Directorate of Mines that the requested actions could only take place after establishing

5840-406: The shepherds picked up elsewhere and sold to dos Santos. When Pinto arrived at the site and saw the abundance of wolframite , he bought all the ore collected and the land from dos Santos, carrying out the first mining registration in the name of Firma Almeida Silva Pinto e Comandita. It was published on 25 November 1898. The work proceeded on a larger scale with the mining of outcropping veins and

5920-569: The situation at the mine, where the inclined radial structures are the precursors of the "galo" veins and the reopening of the sub-horizontal fractures gave rise to the veins. Therefore, it is considered that the vein procession may be an example of a vein field installed during the consolidation phase, in which, due to the cooling of the intrusive massif and dynamic propagation of fractures, sub-horizontal tensile cracks are generated and existing ones reopened. The Panasqueira deposit consists of an extensive field of quartz veins, notable for its size and

6000-405: The stoping operations that led to the use of drilling machines, first with compressed air and then with electro-hydraulic systems. It also allowed the use of loaders, first compressed air, then electrical and currently diesel. The cost of labour and materials associated with using wood piles for total ore recovery is the reason why residual pillars containing 16% of the ore are left behind, leading to

6080-443: The use of scrapers the stopes were adapted into a system of faces converging at the storage and extraction chimney. This variant that in the mine was known as bacalhau ('cod') was doubled. This was the system used throughout most of the 1960s and that resulted in a 40% increase in productivity compared to the initial longwall method. The construction of walls to support the ceiling was a completely manual job and consumed about 60% of

6160-494: The vein field and the fact that Panasqueira's veins are very homogeneous throughout the mineralized zone allowed the systematization and mechanization of mining from the beginning. This was essential for the survival of the mine in a sector that has experienced notable difficulties in recent decades due to changing mining industry patterns in the European Union . The stoping methods used in the mine have varied over time: During

6240-403: The vein field was controlled either by pre-existing fracturing due to early deformation, or by the stress field associated with the granitic intrusion mechanism. The intruding granite heated and elevated the fluid pressure of nearby rocks, causing a network of radial fractures to open around the intrusive massif , allowing entry of granitic rocks into the fractures to form dikes and sills . In

6320-482: The world for decades. They are generally paid at a premium in relation to market prices and chosen by the manufacturers of intermediate or final products where a particular purity of the raw material is required. The Panasqueira mine is also notable in mineral collection due to the size, excellent crystallization and variety of minerals from the mine. In the mine's veins almost all known silicates have been identified, as well as two minerals that have only been found in

6400-435: Was totally unsuitable for grain cultivation. The population of the neighbouring village of Cebola (current São Jorge da Beira) used the folds in the slopes to make terraces where they planted potatoes, corn or pasture. In this manner, small cultivation areas divided into narrow terraces with some fruit trees and large chestnut trees were created in the three small valleys of Madurrada, Vale Torto, and Panasqueira. In Panasqueira

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