  We report the Spitzer Infrared Spectrograph (IRS) observations of three
evolved stars: IRAS 16456-3542, 18354-0638, and 23239+5754. The 9.9--37.2um
Spitzer/IRS high resolution spectra of these three sources exhibit rich sets of
enstatite-dominated crystalline silicate emission features. IRAS 16456-3542 is
extremely rich in crystalline silicates, with >90% of its silicate mass in
crystalline form, the highest to date ever reported for crystalline silicate
sources.
