Cordierite is an orthorhombic silicate. A channel is defined in the structure by rings of AlO4 and SiO4 tetrahedra.
Cordierite is an orthorhombic silicate. A channel is defined
in the structure by rings of AlO4 and SiO4 tetrahedra.
Commercial uses of [synthetic] cordierite.
Cordierite is made by heating clay/water slurries.
Automotive emission catalyst support made from synthetic cordierite |
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References to companies which make cordierite ceramics:
Xiamen Roki Electronics Limited
Color of cordierite
Pleochroism
of cordierite. Crystals placed over a linear polarizer so the the
vibration direction of the light is parallel to different crystallographic
axes.
Cordierite is an example of a mineral with extreme pleochroism (color which varies with the polarization orientation of the incident light). Because cordierite is orthorhombic, there will be three independent absorption spectra obtained with light linerally polarized along the a, b, and c-axes. Most important for determining the visible color is the intervalence charge transfer process (IVCT). This can be seen in the optical absorption spectrum which shows that the IVCT absorption at about 580 nm is most intense in the beta spectrum.
Viking Navigation with cordierite:
Is cordierite the sunstone which Vikings used to navigate the North Alantic?
Article on the sky compass from the University of Alaska
An article discussing the pros and cons of the Viking Sunstone legend.
An article in Applied Optics (broken link) which disputes this idea: Roslund C, Beckman C (1994) Disputing Viking Navigation by Polarized Skylight. Applied Optics 33:4754-.
