Outstanding colorless crystals of the extremely rare and relatively new mineral kircherite (IMA 2009-084) from the type and only known loclaity worldwide: Formello, Biachella Valley, Sacrofano, Latium, Italy. — Photo: David Hospital · CC BY-SA 4.0
Kircherite
Kircherite is an IMA-recognized mineral species in the silicate class, with the chemical formula [Na₅Ca₂K](Si₆Al₆O₂₄)(SO₄)₂·0.33H₂O.
It crystallizes in the hexagonal crystal system (space group R32). It is a member of the Cancrinite structural group.
Key properties: Mohs hardness 5.5; specific gravity 2.42; White streak; Greasy to silky luster; optically uniaxial.
IMA symbol Kcr, IMA status: approved, named in 2009.
A late-stage metasomatic phase within miarolitic cavities in volcanic ejecta.
It is found associated with Sodalite, biotite, iron oxides, titanite, fluorite, an unspecified pyrochlore-group mineral.
The mineral was named to honor Athanasius Kircher (1602-1680), a German Jesuit scholar who published ~ 40 works, some of which dealt with magnetism, geology, mineralogy, and volcanology.