Tilleyite was first described from an occurrence at the Crestmore Quarry in Riverside County, California in 1932 by Esper Larsen and Kingsley Dunham, and named after Cecil Edgar Tilley (1894-1973), a professor of geology at the University of Cambridge, in recognition of his contributions to the study of metamorphism.

[3] Its type material is held at Harvard University, and the National Museum of Natural History.

[5] Tilleyite is formed by contact metamorphism in the zone between volcanics and limestones at low pressure and high temperatures.

Associated minerals include calcite, fluorite, gehlenite, grossular, vesuvianite and wollastonite.

[6] More generally, it occurs at gabbro-limestone contacts, such as at Carlingford, Ireland, and on the island of Muck, Scotland.