The Siilinjärvi carbonatite complex is located in central Finland close to the city of Kuopio. It is named after the nearby town of Siilinjärvi, located approximately 5 km west of the southern extension of the complex. Siilinjärvi is the second largest carbonatite complex in Finland after the Sokli formation, and one of the oldest carbonatites on Earth at 2610±4 Ma. The carbonatite complex consists of a roughly 16 km long steeply dipping lenticular body surrounded by granite gneiss. The maximum width of the body is 1.5 km and the surface area is 14.7 km2. The complex was discovered in 1950 by the Geological Survey of Finland with help of local mineral collectors. The exploration drilling began in 1958 by Lohjan Kalkkitehdas Oy. Typpi Oy continued drilling between years 1964 and 1967, and Apatiitti Oy drilled from 1967 to 1968. After the drillings, the laboratory and pilot plant work were made. The mine was opened by Kemira Oyj in 1979 as an open pit. The operation was sold to Yara in 2007.

Siilinjärvi is a municipality of Finland. It is located in Northern Savonia, 20 kilometres (12 mi) north of the city of Kuopio, which largely surrounds Siilinjärvi. Another neighbour municipality with Kuopio is Lapinlahti. The name, in Finnish, apparently translates literally as "Hedgehog's Lake", although its etymology actually stems from a Sámi word meaning "winter dwelling". Lakes are essential part of the geography of Siilinjärvi. There are 123 lakes, and the biggest of them are Kallavesi and Juurusvesi–Akonvesi. Water area is 106.85 km2, which is 21% of the whole area of Siilinjärvi.