Abstract
Six natural, blue colored spinel crystals were studied chemically by electron microprobe and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) techniques and optically by UV–VIS–NIR–MIR spectroscopy in the range 30,000–2,000 cm−1 to investigate the causes of their blue color hues. The positions of the absorption bands vary only marginally with the principal composition of the samples (gahnite vs. spinel s.s.). Although blue colors in spinels are frequently the result of various electronic processes in Fe cations, we demonstrate by comparison with synthetic Co-bearing samples that Co acts as an important chromophore also in natural spinels. Already at concentration levels of a few ppm (e.g., >10 ppm), cobalt gives rise to absorption bands at ~18,000, 17,000 and 16,000 cm−1 that result in distinct blue coloration. In spinels with insignificant Co contents, different shades of paler blue (from purplish to greenish blue) colors are caused by electronic transitions in TFe2+, MFe2+, MFe3+ and Fe2+–Fe3+ cation pairs.
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Ahmed IS, Shama SA, Moustafa MM, Dessouki HA, Ali AA (2009) Synthesis and spectral characterization of CoxMg1−xAl2O4 as new nano-coloring agent of ceramic pigment Spectrochim Acta A 74:665–672. doi:10.1016/j.saa
Andreozzi GB, Princivalle F, Skogby H, Della Giusta A (2000) Cation ordering and structural variations with temperature in MgAl2O4 spinel: an X-ray single-crystal study. Am Miner 85:1164–1171
Andreozzi GB, Hålenius U, Skogby H (2001) Spectroscopic active IVFe3+–VIFe3+ clusters in spinel-magnesioferrite solid solution crystals: a potential monitor for ordering in oxide spinels. Phys Chem Miner 28:435–444. doi:10.1007/s002690100178
Andreozzi GB, Baldi G, Bernardini GP, Di Benedetto F, Romanelli M (2004) 57Fe Mössbauer and electronic spectroscopy study on a new synthetic hercynite-based pigment. J Eur Ceram Soc 24:821–824. doi:10.1016/S0955-2219(03)00329-7
Bosi F, Hålenius U, D’Ippolito V, Andreozzi GB (2012) Blue spinel crystals in the MgAl2O4–CoAl2O4 series: part II. Cation ordering over short-range and long-range scales. Am Miner 97:1834–1840. doi:10.2138/am.2012.4139
Carbonin S, Martignago F, Menegazzo G, Dal Negro A (2002) X-ray single-crystal study of spinels: in situ heating. Phys Chem Miner 29:503–514. doi:10.1007/s00269-002-0262-6
de Souza LKC et al. (2009) Blue pigments based on CoxZn1−xAl2O4 spinels synthesized by the polymeric precursor method. Dyes Pigments 81:187–192. doi:10.1016/j.dyepig.2008.09.017
Della Giusta A, Carbonin S, Ottonello G (1996) Temperature-dependent disorder in a natural Mg–Al–Fe2+–Fe3+ spinel. Miner Mag 60:603–616
D’Ippolito V, Andreozzi GB, Bosi F, Hålenius U, Mantovani L, Bersani D, Fregola RA (2013) Crystallographic and spectroscopic characterization of a natural Zn-rich spinel approaching the endmember gahnite (ZnAl2O4) composition. Miner Mag 77:2941–2953. doi:10.1180/minmag.2013.077.7.05
Fregola RA, Skogby H, Bosi F, D’Ippolito V, Andreozzi GB, Hålenius U (2014) Optical absorption spectroscopy study of the causes for color variations in natural Fe-bearing gahnite: insights from iron valency and site distribution data. Am Miner 99:2187–2195. doi:10.2138/am-2014-4962
Gaffney ES (1973) Spectra of Tetrahedral Fe2+ in MgAl2O4. Phys Rev B 8:3484–3486. doi:10.1103/PhysRevB.8.3484
Hålenius U, Skogby H, Andreozzi GB (2002) Influence of cation distribution on the optical absorption spectra of Fe3 + -bearing spinel s.s.-hercynite crystals: evidence for electron transitions in VIFe2+–VIFe3+ clusters. Phys Chem Miner 29:319–330. doi:10.1007/s00269-002-0240-z
Hålenius U, Andreozzi GB, Skogby H (2010) Structural relaxation around Cr3+ and the red-green color change in the spinel (sensu stricto)-magnesiochromite (MgAl2O4–MgCr2O4) and gahnite-zincochromite (ZnAl2O4–ZnCr2O4) solid-solution series. Am Miner 95:456–462. doi:10.2138/am.2010.3388
Hofmeister AM (2007) Thermal diffusivity of aluminous spinels and magnetite at elevated temperature with implications for heat transport in Earth’s transition zone. Am Miner 92:1899–1911. doi:10.2138/am.2007.2589
Kock LD, De Waal D (2007) Raman studies of the underglaze blue pigment on ceramic artefacts of the Ming dynasty and of unknown origins. J Raman Spectrosc 38:1480–1487. doi:10.1002/jrs.1805
Lenaz D, Skogby H, Princivalle F, Hålenius U (2004) Structural changes and valence states in the MgCr2O4–FeCr2O4 solid solution series. Phys Chem Miner 31:633–642. doi:10.1007/s00269-004-0420-0
Llusar M, Forés A, Badenes JA, Calbo J, Tena MA, Monrós G (2001) Colour analysis of some colbat-based blue pigments. J Eur Ceram Soc 21:1121–1130. doi:10.1016/S0955-2219(00)00295-8
Longerich HP, Jackson SE, Gunther D (1996) Inter-laboratory note. Laser ablation inductively coupled plasma mass spectrometric transient signal data acquisition and analyte concentration calculation. J Anal Atom Spectrom 11:899–904. doi:10.1039/ja9961100899
Marfunin AS (1979) Physics of minerals and inorganic materials. Springer, New York
Ottinger F, Kroslakova I, Hametner K, Reusser E, Nesper R, Günther D (2005) Analytical evidence of amorphous microdomains within nitridosilicate and nitridoaluminosilicate single crystals. Anal Bioanal Chem 383:489–499. doi:10.1007/s00216-005-0057-y
Princivalle F, Della Giusta A, De Min A, Piccirillo EM (1999) Crystal chemistry and significance of cation ordering in Mg-Al rich spinels from high-grade hornfels (Predazzo-Monzoni, NE Italy). Mineral Mag 63:257–262
Rossman GR, Taran MN (2001) Spectroscopic standards for four- and fivefold-coordinated Fe2+ in oxygen-based minerals. Am Miner 86:896–903
Schmetzer K, Haxel C, Amthauer G (1989) Colour of natural spinels, gahnospinels and gahnites. Neues Jahrb Min Abhdl 160:159–180
Shigley JE, Stockton CM (1984) Cobalt-blue gem spinels. Gems Gem 20:34–41
Skogby H, Hålenius U (2003) An FTIR study of tetrahedrally coordinated ferrous iron in the spinel-hercynite solid solution. Am Miner 88:489–492
Taran MN, Langer K (2001) Electronic absorption spectra of Fe2+ ions in oxygen-based rock-forming minerals at temperatures between 297 and 600 K. Phys Chem Miner 28:199–210. doi:10.1007/s002690000148
Taran M, Koch-Müller M, Langer K (2005) Electronic absorption spectroscopy of natural (Fe2+, Fe3+)-bearing spinels of spinel s.s.-hercynite and gahnite-hercynite solid solutions at different temperatures and high-pressures. Phys Chem Miner 32:175–188. doi:10.1007/s00269-005-0461-z
Taran MN, Koch-Müller M, Feenstra A (2009) Optical spectroscopic study of tetrahedrally coordinated Co2+ in natural spinel and staurolite at different temperatures and pressures. Am Miner 94:1647–1652. doi:10.2138/am.2009.3247
Acknowledgments
The present study benefited from financial support from the Synthesys European Programme at NRM (Swedish Museum of Natural History, Stockholm) and “Progetto Sapienza Avvio alla Ricerca 2012”. P. Patriarca is thanked for kindly providing the samples Nat. 2 and Nat. 4. The assistance of M. Serracino during EMP data collection is gratefully acknowledged. Comments and suggestions by Michail N. Taran and Remo Widmer are highly appreciated.
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D’Ippolito, V., Andreozzi, G.B., Hålenius, U. et al. Color mechanisms in spinel: cobalt and iron interplay for the blue color. Phys Chem Minerals 42, 431–439 (2015). https://doi.org/10.1007/s00269-015-0734-0
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DOI: https://doi.org/10.1007/s00269-015-0734-0