The Bagnold linear dune field investigated by Curiosity at Mount Desert Island (MDI) is in Gale crater, north of the ~5.5 km high Aeolis Mons mound. False-color images (RGB, 2.496, 1.802, and 1.235 μm, respectively) generated from Mars Reconnaissance Orbiter (MRO) Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) data show the dune field has a reddish-brown color. A sand sheet located south of the Bagnold dunes, the Sands of Forvie (SoF), is darker and lacks the reddish-brown color. Single scattering albedo (SSA) spectra retrieved at 12 m/pixel using along‑track oversampled CRISM observation FRT00021C92 show a long wavelength (1.7 to 2.5 μm) rise for the MDI dunes. Over the same wavelength interval, SoF is characterized by a broad ~2.2 μm absorption feature, consistent with color differences between the two deposits. Checkerboard unmixing of the SSA image cube isolated spectral endmembers within the MDI and SoF. Nonlinear modeling using Hapke (2012) theory implies finer grain sizes for MDI compared to SoF, with inferred abundances of basaltic glass > feldspar > olivine > pigeonite > augite for MDI, and basaltic glass > feldspar > augite > olivine for SoF. These results are similar for the mean spectra of each region and coincide with Curiosity‑based observations that MDI contains smaller ripples with overall finer grains, while SoF has large megaripples and concentrated coarser grains on the crests. Although these deposits are only located ~2.5 kilometers away from one another, wind and local topographic controls influence their grain size and mineralogy.