Sand particles from Cancun, Mexico were studied using a number of advanced spectroscopic and microscopic techniques. The main chemical composition of sand particles was confirmed to be calcium carbonate by X-ray photoelectron spectroscopy and IR spectroscopic analysis. X-ray diffraction analysis revealed that the sand particles are aragonite, which has an Orthorhombic-Dipyramidal crystal structure. The morphological study of the sand particles by scanning electron microscopy and transmission electron microscopy revealed the presence of a highly porous channel-like structure in the sand particles. The sorption isotherm indicates that Cancun sand is a mesoporous material. The specific surface area of Cancun sand was determined to be 2.259 m(2)/g by BET measurement, which is significantly higher than that of Florida sand and other forms of natural aragonite and calcite. Furthermore, it was found that the porous sand particles can adsorb gold nanoparticles of the size of a few nanometers very efficiently. The distribution of gold nanoparticles demonstrated a channel-like porous inner structure of the sand particles. We also prepared a polymer composite material by mixing the sand particles with a poly(methyl methacrylate) matrix. SEM analysis of the composite materials showed a good interfacial adhesion between sand particles and polymer matrix. These results suggest that Cancun sand, as a natural macro- and mesoporous material, may find promising applications in filtration, pollution control, composite materials and biomaterials development.