Merlinoite Field of view: 4 mm Locality: Pollena quarries, Pollena Trocchia, Somma Vesuvius Complex, Metropolitan City of Naples, Campania, Italy ( locality at mindat.org ) — Photo: Henk Smeets – tomeikminerals.com · CC BY 4.0
Merlinoite
Merlinoite is an IMA-recognized mineral species in the silicate class, with the chemical formula K₅Ca₂(Si₂₃Al₉)O₆₄·24H₂O.
It crystallizes in the orthorhombic crystal system (space group Immm).
Key properties: specific gravity 2.14–2.27; optically biaxial.
IMA symbol Mrl, IMA status: approved, named in 1976.
Found as a secondary mineral in veins and cavities of silica-undersaturated volcanic rocks (Cupaello, Italy); an alteration product of cataclastized pegmatitic rocks in a differentiated alkalic massif (Khibiny massif, Russia).
It is found associated with Phillipsite, apophyllite, chabazite, calcite.
In honor of Stefano Merlino (1938{), Professor of Crystallography, University of Pisa, Pisa, Italy.