Gejiu (个旧; Hani: Goqjef; Wade-Giles: Ko-Chiu; formerly known as Kotchiu) is a county-level city and the capital of Honghe prefecture, Yunnan Province, China, and has 136,000 inhabitants (ranked 5th largest city in Yunnan). It is the site of the country's largest tin deposits and its main industry is mining.