The mineral bastnasite is one of a family of three carbonate-fluoride minerals. The structure of bastnasite is made up of stacks of carbonate ion layers and cerium fluoride layers. The CeF layers form flat hexagonal sheets with each cerium bonded to three fluorines.

It exhibits a color change showing a strong orange color in incandescent light, but actually shows a yellowish-green color under the light of "energy saver" (mercury-bearing) light bulbs.