Referenza:
▪ Pekov, I.V., Zubkova, N.V., Ksenofontov, D.A., Chukanov, N.V., Yapaskurt, V.O., Korotchenkova, O.V., Chaikovskiy, I.I., Bocharov, V.M., Britvin, S.N., Pushcharovsky, D.Yu. (2018): Redefinition of satimolite. Mineralogical Magazine, 82, (in press).
Abstract:
The borate mineral satimolite, which was first described in 1969 and remained poorly-studied until now, has been re-investigated (electron microprobe analysis, single-crystal and powder X-ray diffraction studies, crystal structure determination, IR spectroscopy) and redefined based on the novel data obtained for the holotype material from the Satimola salt dome and a recently found sample from the Chelkar salt dome, both in North Caspian Region, Western Kazakhstan. The revised idealized formula of satimolite is KNa2(Al5Mg2)[B12O18(OH)12](OH)6Cl4·4H2O (Z = 3). The mineral is trigonal, space group R-3m, unit-cell parameters: a = 15.1431(8), c = 14.4558(14) Å, and V = 2870.8(4) Å3 (Satimola) and a = 15.1406(4), c = 14.3794(9) Å, and V = 2854.7(2) Å3 (Chelkar). The crystal system and unit-cell parameters are quite different from those reported previously. The crystal structure of the sample from Chelkar was solved based on single-crystal data (direct methods, R = 0.0814) and the structure of the holotype from Satimola was refined on a powder sample by the Rietveld method (Rp = 0.0563, Rwp = 0.0761, Rall = 0.0667). The structure of satimolite is unique for minerals. It contains twelve-membered borate rings [B12O18(OH)12] in which BO3 triangles alternate with BO2(OH)2 tetrahedra sharing common vertices, and octahedral clusters [Me7O6(OH)18] with Me = Al5Mg2 in the ideal case, with sharing of corners between rings and clusters to form a three-dimensional heteropolyhedral framework. Each borate ring is connected with six octahedral clusters: three under the ring and three over the ring. Large ellipsoidal cages in the framework host Na and K cations, Cl anions and H2O molecules.
NdR1: Poichè Mg è un elemento essenziale della specie la ridefinizione avrebbe dovuto essere prioritariamente approvata dall'IMA CNMMC.
"Mg2+ is not a predominant constituent in the Al sites but it is an important charge-compensating cation that makes necessary to include Mg in the idealized formula of satimolite".
NdR2: I seguenti borati hanno tutti lo stesso (l.s.) tipo (FBB) di struttura (dodecaborati): il blocco fondamentale è infatti formato da 12 unità: triangoli e tetraedri. Interessante notare che in tutti è presente il Cl.
Brianroulstonite Ca3[B5O6(OH)6]Cl2(OH)·8H2O
Penobsquisite Ca2Fe2+[B9O13(OH)6]Cl·4H2O
Pringleite Ca9[B26O34(OH)24Cl4]·13H2O
Ruitenbergite Ca9[B26O34(OH)24Cl4]·13H2O
Satimolite KNa2(Al5Mg2)[B12O18(OH)12](OH)6Cl4·4H2O
NB: Pringleite e ruitenbergite sono polimorfi.
Redefinition of satimolite
- Marco E. Ciriotti
- Messaggi: 31675
- Iscritto il: ven 25 giu, 2004 11:31
- Località: via San Pietro, 55 I-10073 Devesi/Cirié TO - Italy
- Contatta:
Redefinition of satimolite
Marco E. Ciriotti
«Things are interesting only in so far as they relate themselves to other things»
«Things are interesting only in so far as they relate themselves to other things»
- Marco E. Ciriotti
- Messaggi: 31675
- Iscritto il: ven 25 giu, 2004 11:31
- Località: via San Pietro, 55 I-10073 Devesi/Cirié TO - Italy
- Contatta:
Re: Redefinition of satimolite
Pubblicazione effettuata.
Referenza:
▪ Pekov, I.V., Zubkova, N.V., Ksenofontov, D.A., Chukanov, N.V., Yapaskurt, V.O., Korotchenkova, O.V., Chaikovskiy, I.I., Bocharov, V.M., Britvin, S.N., Pushcharovsky, D.Yu. (2018): Redefinition of satimolite. Mineralogical Magazine, 82, 1033-1047.
Referenza:
▪ Pekov, I.V., Zubkova, N.V., Ksenofontov, D.A., Chukanov, N.V., Yapaskurt, V.O., Korotchenkova, O.V., Chaikovskiy, I.I., Bocharov, V.M., Britvin, S.N., Pushcharovsky, D.Yu. (2018): Redefinition of satimolite. Mineralogical Magazine, 82, 1033-1047.
Marco E. Ciriotti
«Things are interesting only in so far as they relate themselves to other things»
«Things are interesting only in so far as they relate themselves to other things»
Chi c’è in linea
Visitano il forum: Nessuno e 52 ospiti