IMA Commission on New Minerals, Nomenclature and Classiﬁcation (CNMNC) – Newsletter 70

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The information given here is provided by the IMA Commission on New Minerals, Nomenclature and Classification for comparative purposes and as a service to mineralogists working on new species.
Each mineral is described in the following format: mineral name, if the authors agree on its release prior to the full description appearing in press chemical formula (ideal formula) mineral symbol type locality full authorship of proposal e-mail address of corresponding author relationship to other minerals crystal system, space group, structure determined, yes or no unit-cell parameters strongest lines in the X-ray powder diffraction pattern type specimen repository and specimen number citation details for the mineral prior to publication of full description Citation details concern the fact that this information will be published in the European Journal of Mineralogy on a routine basis, as well as being added month by month to the commission's website. It is still a requirement for the authors to publish a full description of the new mineral.
No other information will be released by the commission. Proposal 22-F is accepted. Re-examination of donnayite-(Y) type specimens showed that the original description contains data collected on two different phases with simplified formulae NaCaSr 3 Y(CO 3 ) 6 q 3H 2 O and Na 2 Sr 2 YCe(CO 3 ) 6 q 3H 2 O. The latter corresponds to the recently approved species alicewilsonite-(YCe) (IMA 2020-055). Donnayite-(Y), with the ideal formula NaCaSr 3 Y(CO 3 ) 6 q 3H 2 O, was found in only one specimen -CMNMC 39396 -out of seven housed at the Canadian Museum of Nature, 240 McLeod St, Ottawa, ON K2P 2R1, Canada. This specimen has become the holotype of donnayite-(Y).

IMA 22-G: establishment of the mckelveyite group
Proposal 22-G is accepted, and the mckelveyite group is established. Seven minerals belong to the group: alicewilsonite-(YCe), alicewilsonite-(YLa), bainbridgeite-(YCe), donnayite-(Y), ewaldite, mckelveyite-(Y), and weloganite. Mckelveyite group minerals are carbonates with the general formula A 3 B 3 (CO 3 ) 6 q 3H 2 O, where A = Na, Ca, Y + HREE, Zr, and B = Sr, Ba, LREE. Their structure is based on two alternating layers with larger B cations forming one layer and smaller A cations A forming another. Different order-disorder modifications are known, resulting in triclinic, monoclinic, and trigonal minerals with essentially the same structure.

IMA 22-H: redefinition of bystrite
Proposal 22-H on bystrite is accepted. The mineral bystrite was first described as a trigonal cancrinite-related phase with the simplified formula Ca(Na,K) 7 (Al 6 Si 6 O 24 )(S 2− 3 )1.5 q H 2 O. Initially, two bystrite varieties were distinguished: (i) K-rich and Cl-deficient and (ii) Cl-rich and K-deficient. The latter mineral has been subsequently approved as a separate mineral species, sulfhydrylbystrite, with the formula Na 5 K 2 Ca(Al 6 Si 6 O 24 )S 2− 5 (HS) − . The crystal structure of the presumed Cl-rich and K-deficient bystrite variety shows that this mineral is isostructural with sulfhydrylbystrite and is its analogue with Cl − instead of (HS) − in cancrinite cages, and Na + at the site that is predominantly occupied by K + in sulfhydrylbystrite. The ideal formula of bystrite is consequently redefined as Na 7 Ca(Al 6 Si 6 O 24 )S 2− 5 Cl − .