Hydrothermal vein uranium deposits

The bulk of the world s uranium has been produced historically from (1) lower Proterozoic uraninite placer deposits in quartz-pebble conglomerates, (2) epigenetic uranium deposits in sandstones located in many cases at, or near, groundwater oxidation-reduction interfaces and (3) hydrothermal vein uranium deposits. These three distinctly different geologic environments provided most of the uranium that was produced from the 1940s to the early 1970s and they continue to be important exploration targets in the search for new uranium deposits. 

Coffinite U(SiO, )j (OH),j is a black mineral, important as a uranium ore. It occurs in sandstone deposits and hydrothermal veins. 

In conclusion, uranium deposition is clearly related to two main structural events, both distinguished by widely spaced tension faults with wide vertical displacement.-Two major controls on mineralization have been identified to date— structural (N and N60 E-trending faults) and lithogeochemical (contact between the basement and the Collio formation or its immediate surroundings). The deposit can tentatively be stated to be of the hydrothermal vein type, though some aspects are typical of the vein-like type. ... 

By hydrothermal leaching of granitic rocks containing uranium and subsequent deposition, veins with uranium contents of several percent can be formed. This is the case in deposits at Joachimsthal in Bohemia, at Port Radium in Canada, and at Chin-golobwe in Zaire (Congo Kinshasa). 

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