Trace elements, crystal defects and high resolution electron microscopy

Intergrowth defects (intercalation of different structure types) are common in some rock-forming minerals and can be demonstrated to affect trace element distributions, especially when new crystallographic site types are introduced by the intercalated structure. Atoms that do not readily substitute into the host crystal may be incorporated within the intercalated structure. Trace element partitioning patterns, EPR data and mineral dislocation densities suggest that dislocations do not exercise primary control on the partitioning of compatible trace elements, but the effects of dislocations on incompatible elements may be important. Intergrowth defects in geologically important materials include disordered intergrowth structures in Sulfides and the stacking and chain-width disorder that is found in pyroxenes and amphiboles from a range of occurrences. Intergrowth defects may range from a few Ångstroms wide to optically resolvable size. It is important to evaluate their effects when interpreting geological trace element data.