Håleniusite-(La), chemical formula (La,Ce)OF. is a yellow isometric. It has a dull, earthy lustre. The geological setting of håleniusite-(La) is in vugs -(Ce), intimately intergrown with cerite -(Ce) and bastnäsite -(La).
It was discovered in 1986 at Bastnäs mines, Riddarhyttan, Skinnskatteberg, Sweden and named in honour of Ulf Hålenius , director of the mineralogy department at the Swedish Museum of Natural History in Stockholm.