London and Burt (1982) noted: "... the crandallite invariably occurs at montebrasite borders and probably was the first [secondary] mineral to crystallize. In a typical specimen (Fig. 8), a thin reaction rim of crandallite at montebrasite borders grades outward into veinlets of grayish-white hydroxylapatite, followed by an intergrowth of apatite + muscovite, and finally fine-grained green muscovite at the centers of replacement veinlets and near the crystal boundaries of the primary phase."
