Crystal Brook is a town in South Australia, named after the spring-fed creek next to which it was founded. It is 197 kilometres (122 mi) north of Adelaide and in 2006 had a population of 1,185.
Crystal Brook is situated on Goyder's Line near the border of two climate systems. While apparently cold semi-arid, the town benefits from a temperate mediterranean climate zone near to the east, making possible slightly more intense farming in the region. To the west and north-west lies some marginal, semi-arid farmland. The local farming community still supports many small businesses in the town.
Crystal Brook (or creek) supplied water to the town until 1890 when the Beetaloo Reservoir was completed, which at the time was the largest concrete dam in the southern hemisphere.