  Zeolites are so well known in real world applications and after decades of
scientific study that they hardly need any intro-duction: their importance in
chemistry cannot be overemphasized. Here we add to the remarkable properties
that they dis-play by reporting our discovery that the simplest zeolite,
sodalite, when doped with Cr3+ in the \b{eta}-cage, is a frustrated magnet.
Soft X-ray absorption spectroscopy and magnetic measurements reveal that the Cr
present is Cr(III). Cr(III), with its isotropic 3d3 valence electron
configuration, is well-known as the basis for many geometrically frustrated
magnets, but it is especially surprising that a material like the Ca8Al12Cr2O29
zeolite is a frustrated magnet. This finding illustrates the value of exploring
the properties of even well-known materials families.
