An investigation was undertaken to determine the ages of iron-stained dunes relative to Recent white sand dunes along the northwest Gulf Coast of Florida. Methods of study included heavy mineral counts, sediment color, and scanning electron microscopy of quartz sand micro-textures. Additional scanning electron microscope studies were made of eight heavy mineral species from littoral, eolian, and glacial sediments in order to ascertain the nature of their grain surface microtextures and to evaluate their resistance to weathering processes. Heavy mineral counts of iron-stained dune samples showed decreased abundances of amphibole, epidote, garnet, and, to a certain extent, ilmenite-magnetite in comparison with samples from adjacent unstained dunes. Ratios of combined amphibole, epidote, garnet, and ilmenite-magnetite percentages to combined zircon, rutile, and tourmaline percentages in the O( to 3( sand size fraction indicated that the iron-stained sands studied have undergone the same relative amount of weathering and quite possibly represent contemporaneous eolian deposition. The iron-stained coastal dunes are basically light shades of orange in accordance with the Munsell color system. The color is most likely derived from the in-situ weathering of iron-bearing heavy minerals. Time for iron-stain on sand to develop a specific color in a humid oxidizing environment is uncertain, but it is suggested that progressively older coastal sands tend to be more deeply stained. Microscopic examination of these sands showed the stain to occur as crusty patches, coatings, or iron-stained clay particles. The similarity in colors offered some support for the possibility that the iron- stained dunes had essentially undergone the same amount of weathering through geologic time. Scanning electron microscopy of quartz sand samples from both the Recent and the iron-stained dunes using a new technique suggested by Karpovich for quantitatively expressing grain surface micro-textures revealed that each of the orange sands has approximately the same amount of solution derived surface features. A method of comparing sedimentary deposits by stage of diagenesis/solution suggested that the iron-stained dunes are definitely pre-Recent, and probably Late Pleistocene in age. A preliminary examination of amphibole, epidote. garnet, kyanite, staurolite, tourmaline. and zircon sand grains from littoral, coastal dune. and glacial deposits with the use of the scanning electron microscope demonstrated that surface micro-textures produced as responses to physical and chemical weathering are dependent on mineral crystallography. All of these minerals from the littoral environment had breakage micro-textures that resembled surfaces on glacial quartz. though the fracture surfaces were not as abundant as seen on samples of glacial quartz, epidote. and garrlet, the nature and distribution of the breakage features on heavy mineral sand from beach deposits were shown to be dependent on littoral energy and mineralogy. The heavy minerals amphibole and kyanite displayed surface textures that were controlled marily by cleavage and a process of cleavage initiation was proposed. Amphibole, kyanite, and zircon grains had microtextures which may be derived through eolian transport. No distinctive features derived solely by eolian processes observed on the other minerals. Solution features were on all the minerals studied, and were pronounced on grains from low energy beaches and old coastal dunes. Distinct etch figures were observed on epidote. garnet and tourmaline from littoral environments. Chemical etching by intra-stratal solutions in old coastal dunes affected the unstable minerals epidote and amphibole the most, whereas stabler heavy minerals examined commonly had low relief surfaces.