This data represents laboratory reflectance and emissivity spectral measurements of dune sand samples collected from a variety of dune types and mineralogical compositions from eight dune field locations in Alaska, Arizona, California, Colorado, Idaho, Nevada and New Mexico (labeled and designated as samples DS-1 through DS-8). Each sample were sieved into various size classes and measured both prior to and after sieving. Visible through Near Infrared through Shortwave Infrared (~0.4 - 2.5 microns) reflectance were measured using an artificial light source attached to an Analytical Spectral Devices (ASD) spectrometer. Hemispherical reflectance measurements spanning Mid-IR wavelengths, including the Thermal Infrared (~2.0 - 15.0 microns), were measured using a Nicolet FTIR spectrometer with a gold integrating sphere attachment. These latter measurements were converted from wavenumber to wavelength, and inverted to measure emissivity. TIR spectral measurements were conducted for most of our eight dune samples prior to sieving and does not include measurements of various size fractions, except for one sample (DS-8). VSWIR reflectance measurements are included for each of the full composite samples prior to sieving, as well as selected size fractions after sieving such as the smallest (e.g. pan fraction) and largest measurable size fractions. This metadata entry describes the CSV spectral files associated with sample DS-4, in particular.