Portugal, as the main European source of the element, was put under pressure from both sides, because of its deposits of wolframite ore at Panasqueira.
22.
In addition to copper mines, children with their families participate in artisanal mining of cobalt, wolframite, cassiterite, columbite-tantalite, gold, diamonds.
23.
It is flanked by killas, formed by contact metamorphism, which also contains veins although wolframite and cassiterite is found as a lower percentage of the rock bulk.
24.
Quartz and quartz-feldspar veins form a stockwork with minor mineralisation, whilst greisen bordered veins are found in a sheeted vein system with wolframite and minor cassiterite mineralisation . s
25.
Other examples of series include the olivine series of magnesium-rich forsterite and iron-rich fayalite, and the wolframite series of manganese-rich h�bnerite and iron-rich ferberite.
26.
In April 2009, Brownback introduced the Congo Conflict Minerals Act of 2009 to require electronics companies to verify and disclose their sources of conflict minerals, such as cassiterite, wolframite, and tantalum.
27.
Although reserves of Wolframite and other tungsten ores are believed to remain, the Harding vein beneath Knott has long been worked out and the levels were used for dumping sludge from ore processing operations.
28.
Veins of cassiterite ( tin oxide ) and wolframite ( a mineral containing iron, manganese and tungsten ) are found associated with the greisens, the former deposited by high salinity, low, fluids and the latter by low salinity, high fluids.
29.
Wolframite and arsenic was also produced at the mine, the former accounting for around 50 tons to 150 tons between 1907 and 1956, and the latter between 500 tons and 1000 tons during between 1907 and 1919, declining to 100 tons by 1956.
30.
Reports from 2007 state that 14, 694 tons of cassiterite ( $ 45 million USD ), 1, 193 tons of wolframite ( worth $ 4.27 million USD ) and 393 tons of coltan ( $ 5.42 million USD ) were exported in 2007.
