Uranium ore that is associated with an unconformity. Uranium is often concentrated in sedimentary rocks or precipitated from groundwater, because uranium minerals are readily decomposed under oxidizing conditions. These deposits are all of early Proterozoic age. In Ontario, uranium is con- centrated in the basal bed of the Lorrain Quartzite, which is unconformable on the Archaean granite, the mineralization being about 1 m thick and covering hundreds of square kilometres.
Subjects: Earth Sciences and Geography.