Silky-white fibrous aggregates of very rare hatrurite with minor colorless crystals of ettringite on matrix. From Caspar Quarry, Bellerberg, Ettringen, Eifel, Mayen-Koblenz, Rhineland-Palatinate, Germany. Analyzed by Prof. N. Chukanov. Ex. Erich Laskowski collection (USA). — Photo: David Hospital · CC BY 4.0
Hatrurite
Hatrurite is an IMA-recognized mineral species in the silicate class, with the chemical formula Ca₃SiO₅.
It crystallizes in the hexagonal crystal system (space group Cm).
Key properties: optically biaxial.
IMA symbol Hrr, grandfathered status — known before the IMA’s founding, named in 1977.
Found in a high-temperature contact metamorphic assemblage in a larnite- brownmillerite-mayenite rock, probably derived from fine-grained sediments.
It is found associated with Nagelschmidtite, larnite, brownmillerite, mayenite.
The name refers to the Hatrurim Formation in Israel.