Ancylite is a group of hydrous strontium carbonate minerals containing cerium, lanthanum and minor amounts of other rare-earth elements. The chemical formula is Sr(Ce,La)(CO3)2(OH)*H2O with ancylite-Ce enriched in cerium and ancylite-La in lanthanum. Ancylite was first described in 1899 for an occurrence in the Narsarsuk pegmatite in west Greenland and named from the for curved in reference to its rounded or distorted crystal form.