Sacrofanite is a rare silicate mineral that has the general formula of (Na,Ca)9(Si,Al)12O24(SO4,CO3,OH,Cl)4·n(H2O).
[5] Its name comes from the Sacrofano Caldera in the Monti Sabatini from which it was discovered in Latium, Italy.
[2] It has a hexagonal crystal system, meaning crystallographically it has three horizontal axes of equal length that make an angle of 120° with their positive ends, with a long vertical axis running perpendicular to them.
[2] It occurs as a crystal coating within a vug in a rock ejected from the volcano.
Other minerals occurring in the rock include sanidine, andradite, fassaite, leucite and hauyne.