caa a22 4500 463217365 CHVBK 20180405153201.0 cr unu---uuuuu 170326e20071201xx s 000 0 eng 10.1007/s00269-007-0190-6 doi (NATIONALLICENCE)springer-10.1007/s00269-007-0190-6 The single-crystal, polarized-light, FTIR spectrum of stoppaniite, the Fe analogue of beryl [Elektronische Daten] [Giancarlo Della Ventura, Fabio Bellatreccia, Paolo Rossi] We report here a single-crystal polarized-light study of stoppaniite, ideally (Fe,Al,Mg)4(Be6Si12O36)(H2O)2(Na,□), from Capranica (Viterbo). Polarized-light FTIR spectra were collected on an oriented (hk0) section, doubly polished to 15μm. The spectrum shows two main bands at 3,660 and 3,595cm−1; the former is strongly polarized for E⊥c, while the latter is polarized for E//c. A sharp and very intense band at 1,620cm−1, plus minor features at 4,000 and 3,228cm−1 are also polarized for E//c. On the basis of literature data and considering the pleochroic behavior of the absorptions, the 3,660cm−1 band is assigned to the ν3 stretching mode and the 1,620cm−1 (associated with an overtone 2*ν2 at 3,230cm−1) band to the ν2 bending mode of "type II” water molecules within the structural channels of the studied beryl. The sharp band at 3,595cm−1 is not associated with a corresponding ν2 bending mode; thus it is assigned to the stretching vibration of O-H groups in the sample. The minor 4,000cm−1 feature can be assigned to the combination of the O-H bond parallel to c with a low-frequency metal-oxygen mode such as the Na-O stretching mode. The present results suggest that the interpretation of the FTIR spectrum of Na-rich beryl needs to be carefully reconsidered. Springer-Verlag, 2007 Stoppaniite nationallicence Beryl nationallicence FTIR polarized-light spectroscopy nationallicence H2O/OH nationallicence Della Ventura Giancarlo Dipartimento di Scienze Geologiche, Università Roma Tre, Largo S. Leonardo Murialdo 1, 00146, Roma, Italy aut Bellatreccia Fabio Dipartimento di Scienze Geologiche, Università Roma Tre, Largo S. Leonardo Murialdo 1, 00146, Roma, Italy aut Rossi Paolo Viale dei Promontori 50, 00122, Roma, Italy aut Physics and Chemistry of Minerals Springer-Verlag 34/10(2007-12-01), 727-731 0342-1791 34:10<727 2007 34 269 https://doi.org/10.1007/s00269-007-0190-6 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s00269-007-0190-6 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Della Ventura Giancarlo Dipartimento di Scienze Geologiche, Università Roma Tre, Largo S. Leonardo Murialdo 1, 00146, Roma, Italy aut NATIONALLICENCE 700 1- Bellatreccia Fabio Dipartimento di Scienze Geologiche, Università Roma Tre, Largo S. Leonardo Murialdo 1, 00146, Roma, Italy aut NATIONALLICENCE 700 1- Rossi Paolo Viale dei Promontori 50, 00122, Roma, Italy aut NATIONALLICENCE 773 0- Physics and Chemistry of Minerals Springer-Verlag 34/10(2007-12-01), 727-731 0342-1791 34:10<727 2007 34 269 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer