Cordierite Visible Spectra (generally 350 - 2500 nm)

Images of representative cordierites

The color of cordierite comes from its Fe²⁺ and Fe³⁺. Fe²⁺ in the octahedral site causes the pair of absorption bands near 1000 and 1300 nm which have almost no effect on the color. The strong absorption band in the gamma direction is also from Fe²⁺, but in a different site. The color is predominantly due to the Fe²⁺ - Fe³⁺ intervalance charge transfer band near 600 nm. Sharp bands near 1400 and 1900 nm are from water molecules in channels which run parallel to the c-axis of the crystal.

Visible Spectra: polarizations: (a = alpha direction; b = beta direction; g = gamma direction)

• GRR 262 spectrum; Cordierite, GECO Mine, Manatowage, Ontario, Canada, 0.5 mm thick With type I water dominant. Data Files: a; b; g
• GRR 298 spectrum; Cordierite, Umba River Valley, Tanga, Tanzania. Data Files: a ; b ; c
• GRR 338 spectrum; Cordierite, Mt. Tsilaizina, Madagarcar; 1.0 mm thick. Data Files: a ; b ; c
• GRR 304 spectrum; Cordierite, Snyder Group, North of Naine, Newfoundland and Labrador, Canada, 0.070 mm thick.
• GRR 425 spectrum; Cordierite, Haddam, CT, USA, 0.2 mm thick With type II water dominant. Data Files: a ; b ; g
• GRR 2016 spectrum; Cordiertite, Tamil Nadu, India, plotted as 3 mm thick. Data Files: a ; b ; g
• CIT-7961 spectrum; Cordierite, Dolni Bory, Czech Repubic, plotted as 0.70 mm thick

  Link to a collection of references to mostly color and visible spectroscopy of  cordierite

 Back to the Index of Data Files