Remote sensing analysis of common mafic silicates on bodies like asteroid 433 Eros may be in error unless temperature effects are considered. In this paper, spectral sensitivity to temperature as a function of wavelength from 0.4 to 2.5 microns is quantified using new measurements of reflectance spectra of olivine and two ordinary chondrites. The new data were obtained at higher temperature resolution and with greater accuracy than previous measurements. We use a simple thermal model to show that the temperature difference between terrestrial ambient conditions and those prevailing on main belt asteroids, as well as the temperature variations expected on the surfaces of individual asteroids during observations by spacecraft, are large enough to cause easily detectable spectral differences. Therefore, interpretations of asteroid spectra using spectra of minerals and meteorites obtained at terrestrial ambient conditions are suspect.