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Mineralogical ClassificationNomenclature of the gadolinite supergroup

25th Feb 2018 13:49 UTCMarco E. Ciriotti Manager

Reference:

▪ Bačík, P., Miyawaki, R., Atencio, D., Cámara, F., Fridrichová, J. (2017): Nomenclature of the gadolinite supergroup. European Journal of Mineralogy, 29, 1067-1082.

Abstract:

The newly defined gadolinite supergroup approved by the IMA CNMNC (vote 16-A) includes mineral species that have the general chemical formula A2MQ2T2O8ϕ2 and belong to silicates, phosphates and arsenates. Each site is occupied by: A - Ca, REE (Y and lanthanoids), actinoids, Pb, Mn2+, Bi; M - Fe, □ (vacancy), Mg, Mn, Zn, Cu, Al; Q - B, Be, Li; T - Si, P, As, B, Be, S; and ϕ - O, OH, F. The classification of the gadolinite supergroup is based on the occupancy of A, M, Q, T and ϕ sites and application of the dominant-valency and dominant-constituent rules. The gadolinite supergroup is divided into two groups defined by prevailing charge occupancy at the T site - Si4+ in gadolinite group and P5+ or As5+ in herderite group. The gadolinite group is divided into the gadolinite and datolite subgroups. The A site is dominantly occupied by divalent cations in the datolite subgroup and by trivalent cations in the gadolinite subgroup. Accordingly, the Q site is dominantly occupied by B3+ in the datolite subgroup and by Be2+ in the gadolinite subgroup. The herderite group is divided into two subgroups. The herderite subgroup is defined by the dominant divalent cation (usually Ca2+) in the A site and Be2+ in the Q site, while the M site is vacant. The drugmanite subgroup is defined by the dominance of divalent cations (usually Pb2+) in the A site, vacancy in the Q site and the occupation of the M site. Moreover, “bakerite” is discredited as mineral species because it does not meet the conditions of the dominant-constituent rule.

27th Feb 2018 17:05 UTCFred E. Davis

I have been unable to find this article in Eur. J. Min. (via GeoScienceWorld). In fact, I could not find pages 1067-1082 in vol. 29. The best I could get was a mention of this article in a reference list where it said the article was "in press." If anyone is able to email a pdf copy, please send a PM for my email address. Thanks! Fred

27th Feb 2018 19:03 UTCKnut Edvard Larsen 🌟 Manager

https://www.schweizerbart.de/papers/ejm/list/29#issue6

27th Feb 2018 19:52 UTCFred E. Davis

Thank you, Knut! Oddly enough, GeoScienceWorld isn't current, but your link worked for me.

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