Pitchblende‐bearing vein fillings in the stripa and blanka iron ores

Abstract

Pitchblende‐bearing vein fillings were discovered in the Stripa and Blanka iron ores in 1956 and 1957 respectively. The vein fillings are distinctly younger than the folding of the iron ores and the intrusion of the late‐kinematic Svecofennian granites. The gangue consists of chlorite, quartz and calcite. Pitchblende is the main ore mineral but hematite, pyrite, chalcopyrite, galena, and bornite occur in lesser amounts. The pitchblende often is partially replaced by a low reflectivity pitchblende occasionally associated with some coffinite. The vein fillings are of the same age (1585 my) and paragenetic type as the previously described veins in Uppland (Welin 1964) and confirm the conclusions regarding genesis and ore forming processes which were then made of the uranium mineralization in Central Sweden.