  We present the Infrared Database of Extragalactic Observables from Spitzer
(IDEOS), a homogeneous, publicly available, database of 77 fitted mid-infrared
observables in the 5.4-36um range, comprising measurements for 3335 galaxies
observed in the low-resolution staring mode of the Infrared Spectrometer
onboard the Spitzer Space Telescope. Among the included observables are PAH
fluxes and their equivalent widths, the strength of the 9.8um silicate feature,
emission line fluxes, solid-state features, rest frame continuum fluxes,
synthetic photometry, and a mid-infrared spectral classification. The IDEOS
spectra were selected from the Cornell Atlas of Spitzer-IRS Sources. To our
surprise we have detected at a >95% confidence level crystalline silicates in
the spectra of 786 IDEOS galaxies. The detections range from single band
detections to detections of all fitted crystalline bands (16, 19, 23, 28 and
33um). We find the strength of the crystalline silicate bands to correlate with
the amorphous silicate strength, and the change from an emission to an
absorption feature to occur at higher obscuration as the wavelength of the
crystalline silicate band is longer. These observed characteristics are
consistent with an origin for the amorphous and crystalline silicate features
in a centrally heated dust geometry, either an edge-on disk or a cocoon. We
find the 23 and 33um crystalline silicate bands to be well-suited to classify
the obscuration level of galactic nuclei, even in the presence of strong
circumnuclear star formation. Based on our detection statistics, we conclude
that crystalline silicates are a common component of the interstellar medium of
galactic nuclei.
