Mckelveyite group minerals – Part 1: Nomenclature and new data on donnayite-(Y)
<p>The mckelveyite group consisting of seven carbonate minerals – mckelveyite-(Y), ewaldite, weloganite, donnayite-(Y), alicewilsonite-(YCe), alicewilsonite-(YLa), and bainbridgeite-(YCe) – is formally established. The general formula of the minerals is <span class="inline-formula"...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2023-02-01
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| Series: | European Journal of Mineralogy |
| Online Access: | https://ejm.copernicus.org/articles/35/133/2023/ejm-35-133-2023.pdf |
| Summary: | <p>The mckelveyite group consisting of seven carbonate
minerals – mckelveyite-(Y), ewaldite, weloganite, donnayite-(Y),
alicewilsonite-(YCe), alicewilsonite-(YLa), and bainbridgeite-(YCe) – is
formally established. The general formula of the minerals is
<span class="inline-formula"><i>A</i><sub>3</sub><i>B</i><sub>3</sub></span>(CO<span class="inline-formula"><sub>3</sub></span>)<span class="inline-formula"><sub>6</sub></span> <span class="inline-formula">⋅</span> 3H<span class="inline-formula"><sub>2</sub></span>O, where <span class="inline-formula"><i>A</i>=</span> Na, Ca, Y, and Zr
and <span class="inline-formula"><i>B</i>=</span> Sr, Ba, Ce, and La. Different order–disorder modifications are known
resulting in triclinic, monoclinic, hexagonal, and trigonal minerals with
essentially the same structure. Re-examination of donnayite-(Y) type
specimens shows that the original description contains data collected on two
different species: donnayite-(Y) and alicewilsonite-(YCe). Donnayite-(Y),
NaCaSr<span class="inline-formula"><sub>3</sub></span>Y(CO<span class="inline-formula"><sub>3</sub></span>)<span class="inline-formula"><sub>6</sub></span> <span class="inline-formula">⋅</span> 3H<span class="inline-formula"><sub>2</sub></span>O, was found in only one
specimen out of seven – CMNMC 39396 – housed at the Canadian Museum of
Nature, Ottawa. This specimen becomes the holotype of donnayite-(Y). The
crystal structure of donnayite-(Y) was solved and refined to <span class="inline-formula"><i>R</i><sub>1</sub>=</span> 0.055 for 3366 reflections with <span class="inline-formula"><i>I</i><i>></i>2<i>σ</i>(<i>I</i>)</span>. Donnayite-(Y) is
shown to have a weloganite-type structure confirming its place in the
mckelveyite group.</p> |
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| ISSN: | 0935-1221 1617-4011 |