Sacrofanite
A rare feldspathoid-group silicate approved in 1980, from Italy's Sacrofano volcanic complex.
Intro adapted from Wikipedia (CC BY-SA).
Sacrofanite is an IMA-recognized mineral species in the silicate class, with the chemical formula (Na₆₁K₁₉Ca₃₂)Σ₌₁₁₂(Si₈₄Al₈₄O₃₃₆)(SO₄)₂₆Cl₂F₆·2H₂O.
It crystallizes in the hexagonal crystal system. It is a member of the Cancrinite-sodalite structural group.
Key properties: Mohs hardness 5.5–6; specific gravity 2.423; Pearly luster; optically uniaxial.
IMA symbol Scf, IMA status: approved, named in 1979.
Occurs as crystals lining a cavity in an ejected block of volcanic rock.
It is found associated with Sanidine, andradite, fassaite, leucite, haÄuyne.
The name is taken from the type locality in the Sacrofano volcanic area, Italy.