page_title: Panasqueira
section_title: Mineral associations
hierarchical_section_title: Panasqueira / Geology / Orebody / Mineral associations
caption_attribution_description: Português: Paragénese
context_page_description: Minas da Panasqueira or Mina da Panasqueira is the generic name for a set of mining operations between Cabeço do Pião and the village of Panasqueira, which operated in a technically integrated manner and continue practically since its discovery. Subsequently, it was agglomerated into a single administrative entity called Couto Mineiro da Panasqueira which had its last demarcation on 9 March 1971 and later in the present Exploration Concession C18. The mining installations are currently centralised in the area of Barroca Grande-Aldeia de S. Francisco de Assis i.e. access to underground exploration, extraction and processing of ore.
  The mine has been in operation for almost 120 years in a practically uninterrupted manner, with a strong impact on the identity, history and present society of the Beira Interior. It is also a worldwide reference in the wolfram sector, not only for the quality and volume of production, duration and adaptability of exploration; but also due to the maturity of technical solutions for both underground exploitation and ore processing.
context_section_description: The establishment of a deposition sequence for the minerals of the Panasqueira veins is quite difficult due to the existence of different stages of formation and to the fact that some of them only appear in certain areas of the Couto Mineiro, making their correlation very difficult. However, Kelly & Rye (1979) defined, for the mineralogy of the Panasqueira veins, four stages of deposition:
  1.	Formation Stage of oxides and silicates: it is the most significant stage from an economical point of view, as it is in this one that the formation of wolframite and cassiterite occurs. In this stage, the majority of quartz and muscovite, as well as tourmaline, topaz and a large part of arsenopyrite, are formed in at least two generations.
   
  2.	Formation stage of major sulfides: the predominant minerals are sulphides, especially pyrite, chalcopyrite, sphalerite, stannite and phyrrhotite and, to a lesser extent, galena. One can also find new generations of arsenopyrite, already in a third generation, muscovite and quartz. The final phase of this stage corresponds, essentially, to the end of the deposition of apatite.
   
  3. 	Alteration stage of phyrrhotite: fundamentally characterized by the alteration of phyrrhotite, from which results mainly siderite and marcasite, due to the iron released in the alteration process. Added to this iron is the iron released in the dissolution of the pyrite-I giving rise to a second generation of pyrite, magnetite and hematite. In this phase, alteration of stannite due to reaction with the siderite, forming covellite, chalcopyrite and cassiterite also occurs. It is also at this stage that the silver salts usually associated with bismuthinite and accompanied by sphalerite and / or chalcopyrite are deposited.
   
  4.	Formation stage of late carbonates: characterized by the formation of carbonates, mainly calcite and dolomite, the latter in mixed crystals, that is, with the siderite nucleus, as well as fluorite; it is in this stage that chlorite is formed. Later generations of sulphides were also observed, however, always in small amounts.
caption: Table with Panasqueira paragenesys phases
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