2. Geochemistry and mineralogy

The abundance of scandium in the earth's crust is around 22 ppm (the same order of magnitude as that of lead). Scandium does not combine easily with the common anions that make up minerals, but it is present in very small quantities in over 800 mineral species. Its behavior is similar to that of aluminum, with a strong residual tendency in magmatic processes (pegmatites) and supergene processes (laterites).

Scandium's main mineral species is a silicate, thortveitite, grading around 34% Sc ₂ O ₃ , with the formula Sc ₂ Si ₂ O ₇ , where Sc is partially replaced by Y, Fe, Al. However, other species are known that are mineralogical curiosities,...