Siudaite - a short story of the discovery of another eudialytoid with aberrant manganese behaviour
Last Updated: 5th Oct 2022By Łukasz Kruszewski
Siudaite is yet another representative of the abnormally complex group of cyclosilicates - the eudialyte group, that currently (as of October 2022) counts 32 approved and named mineral species, 22 valid unnamed minerals, and (at least) 3 further unnamed species. The total number of 57 is a good illustration of the extreme complexity and lability of the eudialytoids' structure, where various elements can be found at sites that nominally wouldn't accept such guests.
But that ain't an issue for eudialytes, e.g., to have manganese located at... part of the sodium/alkaline/REE/hydronium sites.
Siudaite was discovered - completely accidentally - during a geological trip of the Young Geologists' (student) Club of the Faculty of Geology, University of Warsaw, in 2008. The trip was called "Saami-blood land" or, more specifically, "In the land where the Saami bloo flows". What is the Saami blood? Eudialyte himself, por supuesto. The "ambassador" of the Khibiny and Lovozero plutons. The idea and organization of this trip came from two of us: the author of this article and Rafał Siuda, who once visited the mighty mighty Kola Peninsula.
During a walk up the Astrofillitovyi stream, of the Astrofillitovyi Gorge (Astrofillitovye Ushchelye), just at the right-hand foot of the first waterfall (bottom of the slopes of Mt. Eveslogchorr), I got interested in a single, ~4-cm-wide rock chunk that excelled in terms of its colour being different than the surrounding. Most of the specimen - the ~3-cm-wide core - was yellowish-orange, with cherry-red rim, both zones surrounded by aegirine.
After homecoming (the world being important in this story, too; see the last paragraph), the speciment began its shelf life, which took about 9 years. After beginning my more-or-less freelance sci-work at the Institute of Geological Sciences PAS, I got re-interested in the specimen, and did PXRD at my then-"owned" PXRD lab. The result wasn't very strange to me: an eudialytoid. Lots of this stuff in both the Khibiny and Lovozero. The material looked exactly as ikranite: yellow-orange core surrounded by cherry-red material. However, after some time, I've ordered thin section and put it into an electron microprobe study. Initially, we though we found a tungsten-rich eudialytoid, based on a single energetic line that was later proven to be coming from silicon. The tungsten sounded strange: Eveslogchorr is quite far away from Kaskasnyunchorr where a W anomaly is known. As such, I was sure I won't be able to provide much more data alone, especially that the eudialytoids are that complex.
I thus sent the specimen, and the thin section, to the best-possible people at the Russian Academy of Sciences, in particular, prof. Ramiza K. Rastsvetaeva (rastsvetaevite). I must admit I was't sure of my move: a Pole sending Russian mineral back to Russia? But the Russian scientist - Mrs Ramiza Rastvetaeva, and the very kind Nikita Chukanov, were happy. Only thanks to their work, and the work of their prominent colleagues, Sergey M. Aksenov, Vyacheslav S. Rusakov, Sergey N. Britvin, Svetlana A. Vozchikova, aproval of siudaite was not only possible, but took place very soon after the study itself.
Siudaite is quite unique as for the eudialytes, in being the first member with manganese in the site(s) nominally attributed to alkaline elements, rare earths, and/or hydronium. This was unprececedented. However, in the beginning of the Russian research, siudaite seemed rather to be a (well known for the researchers) variety of georgbarsanovite. What initially looked like a variety, was however double-checked, in terms of iron valency. This proved not to be, as initially expected, +2, but +3. This trivalency of iron triggered the need of rearrangement of the structural model. As such, manganese "landed" at different site, making the species unique.
Another interesting fact about the species is that it is one of the most hydrated eudialytoids, in terms of the hydration water, i.e., non-proton-bound water. To make the story more complex, the formula of siudaite varied, in the beginning, due to some issues related to location/positioning of (at least?) one of apical oxygen atoms of one of the myriad of coordination polyhedra. Not enough was it for siudaite: some of the sites dedicated for silicon proved to be partially vacant. What a monster!
The story end with two nice additions. First: although the Russian version of the mineral's name starts from "сиуда", this reminds another word - "сюда", which means "here". With this we reach "иди сюда", meaning, "come here". And this is why the name "siudaite", accidentally, reflects its story, of homecoming, back to Russia, to get studied.
Second: I've managed to locate the holotype specimen - as most likely the first such specimen - in the Museum of the Earth, Polish Academy of Sciences (https://mz.pan.pl/en/home-page/).
More:
(1) https://link.springer.com/article/10.1007/s00269-018-0959-9
(2) https://www.researchgate.net/publication/328181632_Homecoming_Siudaite_-_a_New_Mineral_from_the_Khibiny_Massif
(3) https://ras.jes.su/priroda/s207987840000455-9-1-en
But that ain't an issue for eudialytes, e.g., to have manganese located at... part of the sodium/alkaline/REE/hydronium sites.
Siudaite was discovered - completely accidentally - during a geological trip of the Young Geologists' (student) Club of the Faculty of Geology, University of Warsaw, in 2008. The trip was called "Saami-blood land" or, more specifically, "In the land where the Saami bloo flows". What is the Saami blood? Eudialyte himself, por supuesto. The "ambassador" of the Khibiny and Lovozero plutons. The idea and organization of this trip came from two of us: the author of this article and Rafał Siuda, who once visited the mighty mighty Kola Peninsula.
During a walk up the Astrofillitovyi stream, of the Astrofillitovyi Gorge (Astrofillitovye Ushchelye), just at the right-hand foot of the first waterfall (bottom of the slopes of Mt. Eveslogchorr), I got interested in a single, ~4-cm-wide rock chunk that excelled in terms of its colour being different than the surrounding. Most of the specimen - the ~3-cm-wide core - was yellowish-orange, with cherry-red rim, both zones surrounded by aegirine.
At 30% width
At 30% width
After homecoming (the world being important in this story, too; see the last paragraph), the speciment began its shelf life, which took about 9 years. After beginning my more-or-less freelance sci-work at the Institute of Geological Sciences PAS, I got re-interested in the specimen, and did PXRD at my then-"owned" PXRD lab. The result wasn't very strange to me: an eudialytoid. Lots of this stuff in both the Khibiny and Lovozero. The material looked exactly as ikranite: yellow-orange core surrounded by cherry-red material. However, after some time, I've ordered thin section and put it into an electron microprobe study. Initially, we though we found a tungsten-rich eudialytoid, based on a single energetic line that was later proven to be coming from silicon. The tungsten sounded strange: Eveslogchorr is quite far away from Kaskasnyunchorr where a W anomaly is known. As such, I was sure I won't be able to provide much more data alone, especially that the eudialytoids are that complex.
I thus sent the specimen, and the thin section, to the best-possible people at the Russian Academy of Sciences, in particular, prof. Ramiza K. Rastsvetaeva (rastsvetaevite). I must admit I was't sure of my move: a Pole sending Russian mineral back to Russia? But the Russian scientist - Mrs Ramiza Rastvetaeva, and the very kind Nikita Chukanov, were happy. Only thanks to their work, and the work of their prominent colleagues, Sergey M. Aksenov, Vyacheslav S. Rusakov, Sergey N. Britvin, Svetlana A. Vozchikova, aproval of siudaite was not only possible, but took place very soon after the study itself.
Siudaite is quite unique as for the eudialytes, in being the first member with manganese in the site(s) nominally attributed to alkaline elements, rare earths, and/or hydronium. This was unprececedented. However, in the beginning of the Russian research, siudaite seemed rather to be a (well known for the researchers) variety of georgbarsanovite. What initially looked like a variety, was however double-checked, in terms of iron valency. This proved not to be, as initially expected, +2, but +3. This trivalency of iron triggered the need of rearrangement of the structural model. As such, manganese "landed" at different site, making the species unique.
Another interesting fact about the species is that it is one of the most hydrated eudialytoids, in terms of the hydration water, i.e., non-proton-bound water. To make the story more complex, the formula of siudaite varied, in the beginning, due to some issues related to location/positioning of (at least?) one of apical oxygen atoms of one of the myriad of coordination polyhedra. Not enough was it for siudaite: some of the sites dedicated for silicon proved to be partially vacant. What a monster!
The story end with two nice additions. First: although the Russian version of the mineral's name starts from "сиуда", this reminds another word - "сюда", which means "here". With this we reach "иди сюда", meaning, "come here". And this is why the name "siudaite", accidentally, reflects its story, of homecoming, back to Russia, to get studied.
Second: I've managed to locate the holotype specimen - as most likely the first such specimen - in the Museum of the Earth, Polish Academy of Sciences (https://mz.pan.pl/en/home-page/).
More:
(1) https://link.springer.com/article/10.1007/s00269-018-0959-9
(2) https://www.researchgate.net/publication/328181632_Homecoming_Siudaite_-_a_New_Mineral_from_the_Khibiny_Massif
(3) https://ras.jes.su/priroda/s207987840000455-9-1-en
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