Rosenhahnite Locality: Rosenhahnite occurrence, Russian River , Cloverdale [Sonoma County] , Mendocino County , California , USA ( Locality at mindat.org ) Field of view 4 mm. Depth of field is achieved with CombineZM. Specimen and photo Leon Hupperichs. — Photo: Leon Hupperichs · CC BY-SA 3.0
Rosenhahnite
Rosenhahnite is an IMA-recognized mineral species in the silicate class, with the chemical formula Ca₃Si₃O₈(OH)₂.
It crystallizes in the triclinic crystal system (space group P-1).
Key properties: Mohs hardness 4.5–5; specific gravity 2.89; optically biaxial.
IMA symbol Rhh, IMA status: approved, named in 1965.
Found in veins in brecciated, fine-grained, garnet- and diopside-bearing metasediments (Russian River, California, USA).
It is found associated with Pectolite, xonotlite, datolite (Russian River, California, USA); prehnite, gyrolite, okenite, apophyllite (Durham, North Carolina, USA); prehnite, xonotlite.
The name refers to Leo Rosenhahn (1906–1991), amateur mineralogist of San Anselmo, California, USA, who discovered the mineral.