Copper(II) sulfide is a chemical compound with the formula CuS. It consists of copper in the +2 oxidation state and sulfide ions. This compound typically appears as a black solid and is insoluble in water. It is commonly found in nature as the mineral chalcosite and is used in various applications, including electronics and as a semiconductor. In addition to its natural occurrence, copper(II) sulfide can be synthesized in laboratories for research purposes. It plays a role in the production of copper and is also studied for its potential use in solar cells and other electronic devices due to its unique electrical properties.