IMA 2005-014 = dingdaohengite-(Ce)

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Marco E. Ciriotti
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IMA 2005-014 = dingdaohengite-(Ce)

Messaggio da Marco E. Ciriotti » sab 24 set, 2005 10:05

Come la maoniupingite-(Ce), monoclina, C2/m, Fe3+ dominante, IMA 2005-014 è un membro del gruppo della chevkinite: esattamente la fase monoclina, P21/a, Fe2+ dominante.

A IMA 2005-014 è stato dato il nome di dingdaohengite-(Ce).
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Messaggio da Marco E. Ciriotti » sab 24 set, 2005 10:09

Ecco le differenze in formule e dati cristallografici tra le due specie citate nel messaggio precedente:

Dingdaohengite-(Ce) (Ce,La)4Fe2+(Ti,Fe2+,Mg,Fe3+)2Ti2(Si2O7)2O8 mon P21/a (pseudo C2/m) 13.4656 5.7356 11.0977 90.00 100.636 90.00

Maoniupingite-(Ce) (Ce,La,Ca)4(Fe3+,Ti,Fe2+,)(Ti,Fe3+,Fe2+,Nb)4](Si2O7)2O8 mon C2/m 13.385 5.742 11.059 90.00 100.60 90.00
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Messaggio da Marco E. Ciriotti » sab 24 set, 2005 10:35

E ancora - esaudendo una specifica richiesta - tutti i minerali che io classifico nel gruppo della chevkinite, con i dati basici degli stessi:

Chevkinite-(Ce) (Ce,La,Ca,Nd,Pr)4(Fe2+,Mg)Fe3+2(Ti4+,Fe3+,Nb)2(Si2O7)2O8 mon C2/m

Dingdaohengite-(Ce) (Ce,La)4Fe2+(Ti,Fe2+,Mg,Fe3+)2Ti2(Si2O7)2O8 mon P21/a (pseudo C2/m)

Maoniupingite-(Ce) (Ce,La,Ca)4(Fe3+Ti,Fe2+,)(Ti,Fe3+,Fe2+,Nb)4](Si2O7)2O8 mon C2/m

Matsubaraite Sr4TiTi4(Si2O7)2O8 mon P21/a (pseudo C2/m)

Perrierite-(Ce) (Ce,Ca)4(Fe2+,Ca)(Ti4+,Al,Fe3+)2(Si2O7)2O8 mon C2/m

Polyakovite-(Ce) (Ce,La,Nd,Ca)4(Mg,Fe2+)(Cr3+,Fe3+)2(Ti4+,Nb)2(Si2O7)2O8 mon C2/m

Rengeite Sr4ZrTi4(Si2O7)2O8 mon P21/a

Strontiochevkinite (Sr,La,Ce,Ca)4(Fe2+,Fe3+)(Ti,Zr)4(Si2O7)2O8 mon C2/m
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Messaggio da Marco E. Ciriotti » sab 24 set, 2005 11:13

La dingdaohengite-(Ce) è stata dedicata al geologo (e uomo politico) cinese Ding Dao-heng che, nel 1927, scoprì il deposito ferrifero di Bayun Obo, nella Mongolia interna.

DING Dao-heng (1899-1955), born in Zhijin County, Guise Province, was graduated from Department of Geology, Beijing University in 1926 and worked as an assistant where. In 1927, he was invited to join the China North-West Scientific Investigation Group with the members from Chinese Scientific Society and Swedish geographer named Swenhedin and Ding was in Charge of geological research, palaeontological research and investigation on minerals throughout his journey. In July of the same year, Ding found Bayun Obo iron ore. Through primary investigation on the topography, geological structure, cause of the deposit formation,iron ore reserves and constituent, Ding firmly believed that Bayun Obo is a large iron deposit with considerable reserves. In 1933, Ding's paper "Report on Suiyuan Beyunebo Iron Ore" was published in "Geological Report" (No. 23) making Bayun Obo iron ore known to the world firstly. He was studying in Germany in 1935-1938 and then took part in Chuankang Investigation Group.

After the founding of the People's Republic of China, Ding was invited to be the director of Guizhou University Taking Over commission, member of People's Government of Guizhou, member of Army and Government Commission of North-West China, Deputy to the First National People's Congress, member of Central Committee of Jiusanxunshe, Vice director of Chongqing Committee under Central Committee of Jiusanxuanshe, member of Chinese Society of Geology and director of Chongqing Branch of Society under Chinese Society of Geology. Ding's works also include "Records of Xinjiang Minerals", "Exploration Career in Inner Mongolia and Xinjang" and "Minerals in Mengzi and Jingping of Yunnan".
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Messaggio da Marco E. Ciriotti » lun 27 nov, 2006 16:23

La struttura cristallina della dingdaohengite-(Ce) è stata risolta e pubblicata (vedasi referenza in calce).

Referenza:
• Li, Guo-wu, Yang, Guang-ming, Ma, Zhe-sheng, Shi, Ni-cheng, Xiong, Ming, Sheng, Gan-fu, Fan, Hai-fu (2005): The crystal structure of a new mineral dingdaohengite-(Ce). Acta Mineralogica Sinica, 25, 313-320.

... Inutile la pubblicazione l'abstract, scritto in mandarino.
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Messaggio da Marco E. Ciriotti » mer 06 dic, 2006 10:19

In lingua inglese la struttura della dingdaohengite-(Ce) è pubblicata su Acta Geologica Sinica.

Referenza:
• Li, Guo-wu, Yang, Guang-ming, Ma, Zhe-sheng, Shi, Ni-cheng, Xiong, Ming, Sheng, Gan-fu, Fan, Hai-fu (2005): The crystal structure of a new mineral dingdaohengite-(Ce). Acta Geologica Sinica, 79, 325.
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Messaggio da Marco E. Ciriotti » dom 30 mar, 2008 18:44

La descrizione-tipo della dingdaohengite-(Ce) sarà pubblicata su un prossimo numero dell'American Mineralogist.

Referenza:
• Xu, J., Yang, G.G., Li, G., Wu, Z., Shen, G. (2008): Dingdaohengite-(Ce) from the Bayan Obo REE-Nb-Fe Mine, China: Both a true polymorph of perrierite-(Ce) and a titanic analog at the C (1) cite of chevkinite subgroup. American Mineralogist, 93, (in stampa).
Ultima modifica di Marco E. Ciriotti il sab 10 mag, 2008 11:55, modificato 1 volta in totale.
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Messaggio da Marco E. Ciriotti » sab 10 mag, 2008 11:53

La descrizione-tipo della dingdaohengite-(Ce) è ora pubblicata.

Referenza:
• Xu, J., Yang, G.G., Li, G., Wu, Z., Shen, G. (2008): Dingdaohengite-(Ce) from the Bayan Obo REE-Nb-Fe Mine, China: Both a true polymorph of perrierite-(Ce) and a titanic analog at the C (1) cite of chevkinite subgroup. American Mineralogist, 93, 740-744.

Abstract:
Dingdaohengite-(Ce), ideally Ce4Fe2+Ti2Ti2(Si2O7)2O8, is a new member of the chevkinite group minerals from the world-famous Bayan Obo REE-Nb-Fe Mine near Baotou city, Inner Mongolian Autonomous Region, North China. It occurs in the magnesian skarn in the excontact of granite within dolomitic marble. Most individual crystals vary from 0.2 to 1.0 cm in length. Associated minerals are diopside, tremolite, richterite, allanite-(Ce), magnetite, ilmenite, spinel, titanite, pyrochlore, F-rich phlogopite, fluorapatite, quartz, and fluorite, etc. Dingdaohengite-(Ce) is probably of bimetasomatic origin among Ca-Mg-carbonate rock and/or carbonatite, and REE-, F-rich postmagmatic hydrothermal solutions. The mineral is black and becoming brown black in thin fragments. It is translucent to opaque with a submetallic-metallic luster, and a brown streak. It is brittle with conchoidal fracture. No cleavage or parting is observed. Its hardness is VHN25g 606.0–717.4 kg/mm2 (Mohs hardness near 5.9). The measured density is 4.83(7) g/cm3 and the calculated density is 4.88(0) g/cm3. Its reflectance values (for = 589 nm) are 11.4–12.5%. It is biaxial negative. The strongest six X-ray diffraction lines in the powder pattern [d in Å (I) (hkl)] are 2.7524(100)(21), 2.7263(98)(313), 3.1978(68)(212), 2.5460(54)(04), 2.8702(52)(020), and 3.1622(46)(12).
An electron-microprobe analysis on the crystal used to collect X-ray intensity data for crystal-structure refinement gives SiO2 19.29, TiO2 18.26, Al2O3 0.04, FeO 8.49, Fe2O3 1.67, ThO2 0.16, MgO 1.32, CaO 2.17, Nb2O5 0.47, Ta2O5 0.00, La2O3 19.53, Ce2O3 28.08, Nd2O3 n.d., Y2O3 0.00, Na2O 0.00, sum 99.48 wt%; the Fe3+ /Fe2+ ratio was converted by Mössbauer spectroscopy. The empirical formula is (Ce2.13La1.49Ca0.48Th0.01)4.11Fe2+(Ti0.88Fe2+0.47Mg0.41Fe3+0.26 Al0.01) 2.03(Ti1.96Nb0.04)2.00(Si2O7)2O8, based on 22 O atoms with prevalence of Ti in the C1 site of the structure. Dingdaohengite-(Ce) is monoclinic, a = 13.4656(15) Å, b = 5.7356(6) Å, c = 11.0977(12) Å, β = 100.636(2)°, V = 842.39(46) Å3, and Z = 2.
The crystal structure of dingdaohengite-(Ce) was refined with space groups P21/a and C2/m. Pseudo-extinction was found, i.e., reflections with h + k = 2n are systematically strong, while those with h + k = 2n + 1 are weak, which show that the true space group of dingdaohengite-(Ce) is P21/a (pseudo-C2/m).
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Re: IMA 2005-014 = dingdaohengite-(Ce)

Messaggio da Marco E. Ciriotti » sab 16 ago, 2008 14:03

Nell'articolo pubblicato sull'American Mineralogist insistono alcuni errori.
Sbagliata è l'indicazione della referenza proposta IMA: IMA 2007-017 in luogo del corretto numero che è IMA 2007-014.
Errata è anche la tabella 4 a pagina 743.

Referenza:
• Xu, J., Yang, G.G., Li, G., Wu, Z., Shen, G. (2008): Dingdaohengite-(Ce) from the Bayan Obo REE-Nb-Fe Mine, China: Both a true polymorph of perrierite-(Ce) and a titanic analog at the C (1) cite of chevkinite subgroup. American Mineralogist, 93, 740-744.
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Re: IMA 2005-014 = dingdaohengite-(Ce)

Messaggio da Marco E. Ciriotti » mar 17 feb, 2009 10:18

Errata è anche la formula semplificata (o ideale) presente nell'articolo.
La formula "giusta" (dal testo dell'articolo) è la seguente: (Ce,La,Ca,Na,Th)4Fe2+(Ti4+,Fe2+,Mg,Fe3+)2(Ti4+,Fe3+,Nb)2[(Si2O7)O4]2.
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Re: IMA 2005-014 = dingdaohengite-(Ce)

Messaggio da Marco E. Ciriotti » lun 20 lug, 2009 16:12

Neppure la formula "giusta" si rivela corretta in quanto non bilanciata e non rispondente alle risultanze EPMA.
La formula giusta avrebbe dovuto essere: Ce4Fe2+(Fe2+Ti4+)Ti4+2[(Si2O7)O4]2.

Scaturisce comunque evidente la necessità di rivedere l'intero gruppo della chevkinite. L'augurio è che un'apposita sottocommissione riesamini i casi più eclatanti della dingdaohengite-(Ce) e della maoniupingite-(Ce) e definisca per bene la nomenclatura del gruppo.

Referenza:
• Belkin, H.E., MacDonald, R., Grew, E.S. (2009: Chevkinite-group minerals from granulite-facies metamorphic rocks and associated pegmatites of East Antarctica and South India. Mineralogical Magazine, 73, 149-164.
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Re: IMA 2005-014 = dingdaohengite-(Ce)

Messaggio da Marco E. Ciriotti » ven 08 feb, 2019 10:45

Referenza:
▪ Xu, J., Yang, G., Li, G., Wu, Z., Shen, G. (2018): A new mineral, dingdaohengite-(Ce): The polymorph of perrierite-(Ce) and a titanic analog of the C(1) site of chevkinite subgroup. Acta Mineralogica Sinica, 2008, 575.

Abstract:
Dingdaohengite-(Ce),(Ce,La)4Fe2+(Ti,Fe2+,Mg,Fe3+)2Ti2Si4O22, idealy Ce4Fe2+ Ti2Ti2(Si2O7)2O8, monoclinic, a = 13.4656(15) Å, b = 5.7356(6) Å, c = 11.0977(12) Å, β = 100.636(2)°, V = 842.39(46) Å3, space-group P21/a (pseudo - C2/m), Z = 2, is a new member of the chevkinite group minerals from the world-known Bayan Obo REE-Nb-Fe mine in China. The mineral occurs as euhedral or subhedral, short columnar or thick tabular//(001) crystals in the magnesian skarn rocks, located mainly in the exocontact between granite and dolomitic marble. Most individual crystals are 0.2-1.0 cm long, the largest one is 1.5 cm in size. Associated minerals are diopside, tremolite, richterite, allanite-(Ce), magnetite, ilmenite, spinel, titanite, pyrochlore, F-rich phlogopite, fluorapatite, quartz, fluorite, etc. The mineral is black with a brown streak and a submetallic-metallic luster, translucent in thin fragments being brownish-black in colour. It is brittle with conchoidal fractures. No cleavage or parting was observed. Its hardness is VHN25g 606.0-717.4 kg/mm2 (Mohs nearly 5.9). And the measured density is 4.83(7) g/cm3, and the calculated density is 4.88(0) g/cm3. In the reflected light, dingdaohengite-(Ce) is yellowish with gray tone, it is pleochroic with different gray tones, reflectance values (in the case of λ=589nm) are within the range of 11.4%-12.5%. It is biaxial negative. Electron-microprobe analysis of the refined structural crystal gave SiO2 19.29,TiO2 18.26,Al2O3 0.04,FeO 8.49,Fe2O3 1.67,ThO20.16,MgO 1.32,CaO 2.17,Nb2O5 0.47,Ta2O5 0.00,La2O3 19.53,Ce2O3 28.08,Y2O3 0.00,Na2O 0.01, and 99.46 wt% in sum; the Fe3+/Fe2+ ratio was converted by Mossbauer spectroscopy. The corresponding chemical formula is (Ce2.13La1.49Ca0.48Th0.01)∑4.11 Fe2+(Ti0.88Fe2+0.47Mg0.41Fe3+0.2Al0.01)2.03(Ti1.96Nb0.04)∑2.00(Si2O7)2O8, based O=22 apfu (atoms per formula unit) and Ti-occupancy at the C(1) site of the structure from the structural refinement. Certainly, a natural member like dingdaohengite-(Ce) with Ti domination at the C(1) site of the structure in the chevkinite sub-group had not been found before. There exist essentially two different viewpoins on the true space-groups of the chevkinite group, viz., P21/a and C2/m, but a natural material with P21/a space-group in the chevkinite sub-group had not been discovered before, either. For this reason, the crystal structure of dingdaohengite-(Ce) was refined with space-groups P21/a and C2/m, which showed that the true space-group of dingdaohengite-(Ce) is P21/a. In other words, the new mineral is truly a polymorph of perrierite-(Ce). Clearly, the chevkinite-group minerals might have both P21/a and C2/m space-groups.
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Anatoly Kasatkin
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Re: IMA 2005-014 = dingdaohengite-(Ce)

Messaggio da Anatoly Kasatkin » dom 10 feb, 2019 22:10

We had two more discoveries of this rare mineral in S.Urals, Russia:

Kasatkin, A.V., Epanchintsev, S.G., Nestola, F. (2015): Dingdaohengite-(Ce) from Obukhovskiy Uval, South Urals: first find in Russia. Mineralogiya, 3, 3-7.

Kasatkin, A.V., Popov, V.A., Kuznetsov, A.M., Nestola, F. (2017): Dingdaohengite-(Ce) from Vishnevye Mountains (Southern Urals, Russia). Mineralogiya, 3, 3-8.

Here are the links (papers are in russian with english abstracts):
http://baseserv.ilmeny.ac.ru/files/BIBL ... /21296.pdf
http://baseserv.ilmeny.ac.ru/files/BIBL ... /22003.pdf

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Re: IMA 2005-014 = dingdaohengite-(Ce)

Messaggio da Marco E. Ciriotti » dom 10 feb, 2019 23:17

Thanks so much, Anatoly.
All the best.
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