Optical Spectra of Cordierite, Mg₂Al₄Si₅O₁₈

• Grum-Grzhimailo SV (1958) The color of idiochromatic minerals. Zapiski Vserossiiskogo Mineralogicheskogo Obshchestva 87, 129-50. (in Russian)
  

• Farrell EF, Newnham RE (1967) Electronic and vibrational absorptoin spectra in cordierite. American Mineralogist 52, 380-388. 
• Faye GH, Manning PB, Nicker EH (1968) The polarized optical absorption spectra of tourmaline, cordierite, chloritoid and viviianite: ferric-ferrous electron interaction as a source of pleochroism. American Mineralogist 53, 1174-1201. 1968.
• Robbins DW, Strens RGJ (1968) Polarization-dependence and oscillator streingths of metal-metal charge-transfer bands in iron (II,III) silicate minerals. Chemical Commications 1968, 508-509.
  

• Faye GH (1972) Relationship between crystal-field splitting parameter "deltaVI" and M_host-O bond distance as an aid in the interpretation of absorption spectra of Fe²⁺-bearing materials. Canadian Mineral 11, 473-487. 
• Sengupta D (1975) Interpretation of the polarized absorption spectra of cordierite. Indian J Pure Appl Phys 13: 857-859.
• Smith G, Strens RGJ (1976) Intervalence transfer absorption in some silicate, oxide and phosphate minerals. In: Strens RGJ (ed) The physics and chemistry of minerals and rocks. Wiley, New Your, pp 583-612. 
• Goldman DS, Rossman GR, Dollase WA (1977) Channel constituents in cordierite. American Mineralogist 62, 1144-1157.
• Smith G (1977) Low-temperature optical studies of metal-metal charge-transfer transitions in various minerals. Canadian Mineralogist 15, 500-507.

• Bakhtin AI (1980) Absorption spectra and crystal chemistry of iron in cordierite (in Russian). Geokhimiya 1980:, 1110-1113. 
• Vance ER, Price DC (1984) Heating and radiation effects on optical and Moessbauer spectra of iron-bearing cordierites. Physics and Chemistry of Minerals 10, 200-8. 
• Solntsev VP, Demina TV, Mikhailov MA (1985) Isomorphism of some iron-​group ions in compounds with a beryl structure based on EPR. Trudy Instituta Geologii i Geofiziki (Novosibirsk) 610, 121-8. 

• Langer K, Khomenko VM (1999) The influence of crystal field stabilization energy on Fe²⁺ partitioning in paragenetic minerals. Contributions to Mineralogy and Petrology 137, 220-231.
  

• Geiger CA, Armbruster T, Khomenko V, Quartieri S (2000) Cordierite I: the coordination of Fe²⁺. American Mineralogist 85, 1255-1264. 
• Khomenko VM, Langer K, Geiger CA 92001) Structural locations of the iron ions incordierite: a spectroscopic study. Contributions to Mineralogy and Petrology 141, 381-396.
• Taran MN, Langer K (2001) Electronic absorption spectra of Fe2+ ions in oxygen-based rock-forming minerals at temperatures between 297 and 600 K.Physics and Chemistry of Minerals 28, 199-210.
• Taran MN, Rossman GR (2001) Optical spectroscopic study of tuhualite and a re-​examination of the beryl, cordierite, and osumilite spectra. American Mineralogist 86, 973-980.         

• Hanus R, Kusa I, Kasikova J (2016) Gem-quality sekaninaite from the Czech Republic. The Journal of Gemmology 35, 148-154.

• Hreus S, Novák M, Štubňa J (2022) Iolite from the Czech Republic.The Journal of Gemmology 38, 12-14.
• Liu X, Guo Y (2022) Study on the Color-Influencing Factors of Blue Iolite. minerals 12. 1356. https://doi.org/10.3390/min12111356
• Yan W, Zhou Z, Rao Y, Guo Q (2024) Gemological Characteristics of Blue-Violet Cordierite. Crystals 14, 637; https://doi.org/10.3390/cryst14070637

Optical Spectra of Sekaninite, Fe₂Al₄Si₅O₁₈      

• Goldman DS, Rossman GR, Dollase WA (1977) Channel constituents in cordierite. American Mineralogist 62, 1144-1157.
• Taran MN, Langer K (1998) Temperature and pressure dependence of intervalence charge transfer bands in spectra of some Fe- and Fe,Ti-bearing oxhygen-based minerals. Neues Jahrbuch für Mineralogie - Abhandlungen 172, 325-346
  
• Hanus R, Kusa I, Kasikova J (2016) Gem-quality sekaninaite from the Czech Republic. The Journal of Gemmologoy 35, 148-154.