Micro-heterogeneity of uraninite

Studies of the crystallochemical characteristics of quadrivalent-uranium minerals, in particular of uraninite, have shown that their instability is due to several processes, including oxidation auto-oxidation, and hydration, often superimposed on one another. As a result of these processes, hexavalent uranium is also found in the mineral, causing structural deformation (2) and a change in the mineral's physical and optical properties. The correlation between the reflectance and microhardness of uraninite and its degree of oxidation as defined by its oxidation coefficient, was previously studied. An increase in the degree of oxidation is coupled with a decrease in reflectance and microhardness. Along with this regular relationship, it was also found that samples with high reflectance have decreased microhardness and low reflectance samples have high microhardness. Reasons for these deviations were not discovered. 3 references, 3 figures, 1 table