Mineral, accessory formation

The elements for which the results can be underestimated because of an incomplete digestion of refractory accessory minerals such as zircon and garnet, and/or formation of insoluble fluoride complexes have been distinguished. Recommendations on the choice of the decomposition procedure for such samples are given. 

De Putter, T., Andre, L., Bernard, A., Dupuis, C., Jedwab, J., Nicaise, D. Perruchot, A. 2002. Trace element (Th, U, Pb, REE) behaviour in a cryptokarstic halloysite and kaolinite deposit from Southern Belgium importance of accessory mineral formation for radioactive pollutant trapping. Applied Geochemistry, 17, 1313-1328. 

Abbreviations AF = amphibolite faeies BIF = banded iron formation BSF = bluesehist facies GF = granulite faeies GG = granitic gneiss or chamockite GSF = greenschist facies RAM = refractory accessory mineral thermometer Qtzt = quartzite. 

Armstrong JT (1984) Qnantitative analysis of sihcate and oxide minerals a reevaluation of ZAF corrections and proposal for new Bence-Albee coefficients. Microbeam Anal-1984 19 208-212 Bastin GF, vanLoo FJJ, Heijhgers HIM (1984) An evaluation of the use of Gaussian prz curves in quantitative electron probe microanalysis. X-Ray Spectrom 13 91-97 Bea F, Montero P (1999) Behavior of accessory ph e and redistribution of Zr, REE, Y, Th, and U during metamorphism and partial melting of metapelites in the lower cmst an example from the Kinzigite Formation of Ivrea-Verbano, NW Italy. Geochim Cosmochim Acta 63 1133-1153... 

In geological formations, the content of heavy minerals may vary from 0 to 100%, and there is a tendency for some heavy mineral species to occur preferentially in certain kinds of rock. In any rock the minerals may be divided into primary and secondary rock minerals according to their origin. Primary rock minerals were formed at the same time as the rock containing them, while secondary rock minerals were formed as a result of reactions taking place within the host rock at some time after its formation. Rock-forming minerals may also be classified as essential or accessory. Essential minerals are those implied in the definition of the rock name, while accessory minerals are additional to the above definition, so that their absence would not necessitate a change in the rock name. Heavy minerals as they occur in rocks may be essential or accessory they are usually primary, but occasionally they are secondary. 

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