Trace element distribution rules

However, the lack of generality of the trace element distribution rules, par-... 

Trace element distribution rules. Attempts to explain the distributions of transition metal ions in crustal rocks and minerals by empirical rules based on... 

Bums, R. G. Fyfe, W. S. (1967) Trace element distribution rules and their significance. Chem. Geol., 2, 89-104. 

On the basis of ion size and charge, Goldschmidt deduced certain principles governing trace element distribution. The principles have become known as the Goldschmidt Rules. They are ... 

Numerous attempts have been made by geochemists to account for the ways in which trace elements distribute themselves. It has not been possible to define the energies of different possible locations of trace elements so that their equilibrium distributions can be accurately predicted. There are primitive notions, e.g., that the lanthanides merely follow calcium, that are too crude to be of much use, although there is a grain of truth in them. The most useful rule is that lanthanides (and other trace cations) readily enter those sites in crystals normally occupied by more common cations of approximately equal ionic radius (e.g., Neumann et al., 1966). Effects on lanthanide behavior of balancing charge in the event that the cation substituted for was not 3-1- seem to be second order for chemically complex natural systems as long as lanthanide concentrations are low (tens of ppm or less). 

The various rules that were enunciated to explain element distributions and partitioning in crystal/melt systems have had a profound influence in crystal chemistry and on interpretations of trace element geochemistry. They have served as useful guiding principles for predicting mineral occurrences and explaining the locations of trace elements in crystal structures. Thus, given the ionic radius and valence of a trace element, assessments can be made of the crystal structures most likely to accommodate that element. Well-known examples include... 

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