Abstract
AbstractA nomenclature scheme has been set up for the nordite supergroup of minerals, which have the general formula A2BXYZT6O17 and where A = Na; B = Na, Ca; X = Sr, Ca, Ba; Y = REE, Sr; Z = Zn, Fe, Mn, Mg and T = Si. The nordite supergroup includes nordite-(La), nordite-(Ce), ferronordite-(La), ferronordite-(Ce) and manganonordite-(Ce), as well as meieranite which is considered as an unassigned member of the nordite supergroup. In the known nordite-group minerals the Y site is occupied by rare earth elements (REE), while in meieranite the Y site is occupied by Sr. The dominant element on the tetrahedral Z site determines the prefix used in the mineral name. New rootnames must be given to species with a different dominant element on the A, B or X sites. Nordite supergroup minerals are orthorhombic, although nordite-group minerals and meieranite crystallise in the Pcca and P21nb space groups, respectively. The proposed nomenclature scheme for the nordite supergroup has been approved by the Commission on New Minerals, Nomenclature and Classification (CNMNC) of the International Mineralogical Association (IMA). In addition, new chemical and structural investigations were performed on nordite-(Ce) from Illutalik (Igdlutalik), South Greenland, leading to the first crystal structure refinement for nordite-(Ce).
Highlights
The first nordite species was discovered in Pegmatite No 65 located in the Chinglusuai river valley, Lovozero alkaline complex, Kola Peninsula, Russia (Gerasimovsky, 1941)
During a study of nordite-group minerals from the Ilímaussaq alkaline complex, South Greenland (Gulbransen, 2020) it became apparent that the nordite-(Ce) from Illutalik (South Greenland) published by Upton et al (1976) should be re-investigated as the chemical data results in an empirical formula with significant deviation from the ideal composition
Following the recommendations of Mills et al (2009) on the standardisation of mineral group hierarchies we propose the establishment of the nordite supergroup, subdivided into
Summary
The first nordite species was discovered in Pegmatite No 65 located in the Chinglusuai river valley, Lovozero alkaline complex, Kola Peninsula, Russia (Gerasimovsky, 1941). During a study of nordite-group minerals from the Ilímaussaq alkaline complex, South Greenland (Gulbransen, 2020) it became apparent that the nordite-(Ce) from Illutalik (South Greenland) published by Upton et al (1976) should be re-investigated as the chemical data results in an empirical formula with significant deviation from the ideal composition.
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