The Mineralogy of Interstellar and Circumstellar Dust in Galaxies

Dust in space is ubiquitous and is part of the cycle of matter in galaxies. The observed properties of dust change as a function of the astrophysical environment in which it is found. Dust can therefore be used as a tracer and probe of the physical and chemical conditions where it is detected. We present an observational overview of interstellar and circumstellar dust using spectroscopy at infrared wavelengths. Thanks to the contributions made by space-based infrared spectrographs, a large observational database of dust in space is now available. In this review, we focus on the identification of solid state resonances at these wavelengths, and present an inventory of dust species in different astrophysical environments. The picture that emerges is that of a very rich circumstellar dust mineralogy, while the interstellar medium shows only a limited amount of species. The implications for our understanding of dust processing in different astrophysical environments are also discussed.