Visible, near-infrared (VNIR) reflectance spectra and midinfrared (MIR) transmission spectra (2.5--25. μm) were measured for selected rock types from disseminated gold and silver deposits in northern Nevada and southern Idaho. Samples from the open-pit mines in Pinson, Nevada, and Delmar, Idaho, were compared to weathered surface samples from a prospect at Preble, Nevada. Eight characteristics of the disseminated deposits were proposed that could be identified by remote-sensing applications. Of these eight characteristics, jasperoids, the siliceous replacement of limestones were readily distinguishable from the carbonate host rock and other associated silicate rocks by their spectral characteristics in the MIR. Active or fossil hot-spring sites, where present near the deposit, display similar VNIR spectral features at the surface as hydrothermally altered rocks found at depth in the open-pit mines. However, most of the host rocks at the surface above a disseminated gold prospect show few VNIR absorption features, because of the presence of organic matter. VNIR spectral features of carbonate were detectable in a few cases immediately adjacent to a jasperoid. Ammonium spectral features are observed on some of the hydrothermally altered shale surrounding the prospect, also suggesting the presence of organic matter. Because organic matter exerts such a large influence on the spectral character of the host rocks, the combined MIR and VNIR wavelengths are needed for remote discrimination of disseminated gold prospects in the western U. S.