Chalcocite Cu 2 S particles have been prepared hydro- and solvo-thermally from a copper plate in pure water, mixed solvents of water and ethylenediamine (en), and pure en, respectively. Their structural and optical properties have been characterized by a combination of powder X-ray diffraction, scanning and transmission electron microscopy (SEM and TEM), and VIS-NIR diffuse reflectance spectroscopy. Their growth and optical properties were found to be highly dependent on synthesis conditions and in particular the en/water volume ratio. For the first time, Cu 2 S particles wish the shape of hexagonal microdisks were synthesized in a mild hydrothermal condition and these crystalline particles were found to exhibit unique optical properties.