Compounds of the crandallite type comprise a natural mineral group reaching from proper crandallite CaAl 3(OH) 6(HPO 4)(PO 4) over woodhouseite CaAl 3(OH) 6(SO 4)(PO 4) to alunite KAl 3(OH) 6(SO 4) 2.
纤磷钙铝石类化合物系由自纤磷钙铝石CaAl3 (OH) 6(HPO4) (PO4)本身、经磷钙铝石CaAl3 (OH) 6(SO4) (PO4)到钾明矾石KAl3 (OH ) 6(SO4) 2 等的天然矿物族所组成的。