Fibrous aggregates of the magnesium silicate mineral spadaite from California: Palos Verdes Hills, Los Angeles County, California, United States of America. — Photo: David Hospital · CC BY-SA 4.0
Spadaite
Spadaite is an IMA-recognized mineral species in the silicate class, with the chemical formula MgSiO₂(OH)₂·H₂O.
Key properties: Mohs hardness 2.5; specific gravity 2.2; Pearly or greasy luster; optically biaxial.
IMA symbol Spa, IMA status: questionable, named in 1843.
Found in leucite-bearing lava (Capo di Bove, Italy); in amygdular diabase (Sasbach, Germany); replacing tactite minerals near gold ore shoots (Gold Hill, Utah, USA).
It is found associated with Wollastonite, diopside, garnet.
The name refers to Lavino Spada de Medici (1801–1863), Italian political figure interested in mineralogy.