It is found in hydrothermal deposits left in calcareous rocks, often formed as a result of secondary mineralization.

It forms at a temperature of about 100 °C (212 °F), and becomes unstable above about 150 °C (302 °F), and so its presence in sedimentary rocks indicates that these have experienced intermediate diagenesis.

It was first named lomonite by R. Jameson (System of Mineralogy) in 1805, and laumonite by René Just Haüy in 1809.

It is named after Gillet de Laumont who collected samples from lead mines in Huelgoat, Brittany, making them the type locality.

Notable occurrences are India; Paterson, New Jersey; Pine Creek, California; Iceland; Scotland; and the Bay of Fundy, Nova Scotia.