Cu2S, or copper(I) sulfide, is a chemical compound composed of copper and sulfur. It typically appears as a dark brown or black solid and is known for its semiconductor properties. Cu2S is often found in nature as a mineral called chalcocite, which is an important ore of copper. In industrial applications, Cu2S is used in the production of copper metal through processes like smelting. It can also serve as a precursor for other copper compounds. Additionally, Cu2S plays a role in photovoltaic cells, contributing to the development of solar energy technologies.