Panasqueira Mines, Covilhã, Castelo Branco District, Portugal
|Latitude & Longitude (WGS84):||40° 9' 14'' North , 7° 44' 52'' West|
|Latitude & Longitude (decimal):||40.15395,-7.74786|
|Other regions containing this locality:||Iberian Peninsula|
|Köppen climate type:||Csb : Warm-summer Mediterranean climate|
|Name(s) in local language(s):||Couto Mineiro da Panasqueira, Covilhã, Distrito de Castelo Branco, Portugal|
Mine Information: A large tin-tungsten mine made up of multiple concessions that started production in 1898. Mining is in gently dipping stacked quartz veins that lead into mineralized wolfram-bearing schist. The mineralized zone has dimensions of approximately 2,500 m in length, varying in width from 400 m to 2,200 m, and continues to at least 500 m in depth.
Originally the longwall method or a variant with partial filling was used, but in 1986 it was changed to room-and-pillar based on an analysis of geological and geomechanical characteristics of the rock mass.
Access to the mine's main levels is by a 2.5 m x 2.8 m decline from the surface at a 14% grade. The main levels consist of a series of parallel drives that are spaced 100 m apart and which provide access to the ore passes for rail transport, and connect with ramps for movement of drilling and loading equipment.
Blocks of ore are laid out initially in 100 m x 80 m sections by driving 5 m wide tunnels, 2.2 m high. Similar crosscuts are then set off at right angles to create roughly 11 m by 11m pillars, which are ultimately trimmed to 3 m by 3 m, providing an extraction rate of 84%. Blasted ore is loaded from the stopes by a fleet of LHDs (rubber tired low profile loaders), tipping into 1.8 m-diameter bored raises connecting to the main level boxes. Rail haulage with trolley locomotives is used to transport the ore to the shaft on Level 3, and to the 900 t-capacity main ore pass on Level 2 that provides storage for the 190 metric ton/hour jaw crusher located at the 530 m-level.
Geology: Panasqueira granite intrudes Precambrian marine shales, greywackes, and sandstones. Shales are converted into biotite cordierite andalusite hornfelses near the granite contact. Irregular barren quartz masses were formed in shales (quartz segregation lenses) during Hercynian (the geologic mountain-building event caused by the Late Paleozoic continental collision between Euramerica and Gondwana to form the supercontinent of Pangaea) regional metamorphism. Panasqueira muscovite-albite leucogranite batholith evolves upwards into a quartz-greisen cupola overlain by a quartz cap, from which related quartz veins (stockscheider) penetrate into the shales. Later subhorizontal mineralized veins follow these quartz veins.
Four stages of mineralization are known:
1) Oxide-silicate stage (280-320°C): ferberite, cassiterite in quartz veins, arsenopyrite, topaz, muscovite and tourmaline
2) Sulfide stage: arsenopyrite, pyrite, pyrrhotite, chalcopyrite, sphalerite, stannite, etc.
3) Pyrrhotite alteration stage
4) Carbonate stage: calcite and dolomite, minor sulfides
Mineral ListMineral list contains entries from the region specified including sub-localities
75 valid minerals. 2 (TL) - type locality of valid minerals. 2 erroneous literature entries.
This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.
Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org
541 - 1000 Ma
|Neoproterozoic sedimentary rocks|