Pegmatites uranium

Intrusive Deposits. Deposits included in the intmsive deposit type are those associated with intmsive or anatectic rocks of different chemical composition, eg, alaskite, granite, monzonite, peralkaline syenite, carbonatite, and pegmatite. Examples include the uranium occurrences in the porphyry copper deposits such as Bingham Canyon and Twin Butte in the United States, the Rossing Deposit in Namibia, and Ilimaussaq deposit in Greenland, Palabora in South Africa, and the deposits in the Bancroft area, Canada (15). 

Keywords uranium, granitic pegmatite, Lac Turgeon, Grenviiie Province, Quebec... 

In addition to the examples listed above, uranium mineralization occurs in several other geological settings in and around the CMB, including within granitoid plutonic rocks and as possible syngenetic mineralization in felsic volcanic rocks of both the Aillik and Bruce River groups. Pegmatite-hosted uranium mineralization is also known in deeper-level reworked Archean basement terranes. 

That the atomic weight of uranium lead is extremely variable has already been shown. In order to interpret this variability its sources must be studied both geologically and mineralogically. On the geologic side of the question the uranium ore can be divided in to three principal classes, which are sharply distinct. The definitely crystallized varieties of uraninite occur in coarse pegmatites, associated with feldspar, quartz, mica, beryl, and other minor accessories. The massive pitchblende is found in metalliferous veins, together with sulphide ores of copper, lead, iron, zinc, and so forth. As for camotite, that is a secondary mineral, found commonly as an incrustation on sandstone, and often, also upon fossil wood. There may be other modes of occurrence, but these are the most distinctive. 

On the weathering of pegmatites containing uranium, secondary concentrations are formed, in which uranium is oxidized to the hexavalent stage. Water-soluble uranyl complexes are enriched in clays and phosphates. In sandstones, uranyl-con-taining solutions may again be precipitated under reducing conditions and form... 

---