Green andradite stones: gemmological and mineralogical characterisation (Articolo in rivista)

Type
Label
  • Green andradite stones: gemmological and mineralogical characterisation (Articolo in rivista) (literal)
Anno
  • 2011-01-01T00:00:00+01:00 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#doi
  • 10.1127/0935-1221/2011/0023-2079 (literal)
Alternative label
  • ILARIA ADAMO1, G. DIEGO GATTA1,2,*, NICOLA ROTIROTI1,2, VALERIA DIELLA2 and ALESSANDRO PAVESE1,2 (2011)
    Green andradite stones: gemmological and mineralogical characterisation
    in European journal of mineralogy (Print)
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • ILARIA ADAMO1, G. DIEGO GATTA1,2,*, NICOLA ROTIROTI1,2, VALERIA DIELLA2 and ALESSANDRO PAVESE1,2 (literal)
Pagina inizio
  • 91 (literal)
Pagina fine
  • 100 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroVolume
  • 23 (literal)
Rivista
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#pagineTotali
  • 9 (literal)
Note
  • Scopus (literal)
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  • 1 Dipartimento di Scienze della Terra, Universita` degli Studi di Milano, Via Botticelli 23, I-20133 Milano, Italy 2 CNR-Istituto per la Dinamica dei Processi Ambientali, Sezione di Milano, Via Botticelli 23, I-20133 Milano, Italy (literal)
Titolo
  • Green andradite stones: gemmological and mineralogical characterisation (literal)
Abstract
  • Amulti-methodological investigation of natural gem-quality andradite crystals occurring in serpentinites (ValMalenco, Italy; Nizhniy Tagil, Russia; Kerman, Iran, and Kaghan, Pakistan), or in skarn rocks (Erongo, Namibia, and Antetezambato, Madagascar) has been performed by means of gemmological standard testing, electron-microprobe chemical analyses in wavelength-dispersive mode (EMPA-WDS), ultraviolet, visible and near-infrared (UV-Vis-NIR) and mid-infrared (MID-IR) spectroscopy, and single-crystal X-ray diffraction, in order to describe the gemmological properties and the crystal chemistry of these marketable green stones. The EMPAWDS data show that these green garnets are almost pure andradite [Adr(Ca3Fe2Si3O12).96.1 mol%]. The Cr-content ranges, as Cr2O3, from,0.01 up to?1.0 wt%. This chromophore element, if present, influences the garnet's colour, which is mainly due to Fe3þ. The Cr-content does not affect the unit-cell constant, at least within the range found here. The refined electron content at the Fe-site suggests that chromium occupies the octahedral site along with iron, as found in previous investigations. The MID-IR spectra show the presence of hydroxyl groups. The refined site occupancy factors of the Si-site, modelled with the scattering curve of silicon alone, range between 99.2(4) and 99.9(2), which barely suggests potential hydrogarnet substitution [i.e., (SiO4)4? $ (O4H4)4?]. (literal)
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