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Abstract. A library of thermal infrared spectra of silicate, carbonate, sulfate, phosphate, halide, and oxide minerals has been prepared for comparison to spectra obtained from planetary and Earth-orbiting spacecraft, airborne instruments, and laboratory measurements. The emphasis in developing this library has been to obtain pure samples of specific minerals. All samples were hand processed and analyzed for composition and purity. The majority are 710-1000/am particle size fractions, chosen to minimize particle size effects. Spectral acquisition follows a method described previously, and emissivity is determined to within 2% in most cases. Each mineral spectrum is accompanied by descriptive information in database form including compositional information, sample quality, and a comments field to describe special circumstances and unique conditions. More than 150 samples were selected to include the common rock-forming minerals with an emphasis on igneous and sedimentary minerals. This library is available in digital form and will be expanded as new, well-characterized samples are acquired. MethodSamples were prepared through a process of crushing, sieving, and washing. Crushing was done either by hand using a rock hammer or through a jaw crusher. Samples were then dry-sieved using a Ro-tap mechanical sieve shaker, and the 710-1000/am size fraction was separated. This size fraction was used because volume scattering effects that are introduced 9735