Several colorless single crystals of the very rare K- borate mineral santite in a capsule. From Larderello, Pomarance, Pisa Province, Tuscany, Italy. Ex Vandenbroucke Museum collection from Waregem, Belgium. — Photo: David Hospital · CC BY 4.0
Santite
A hydrated potassium borate from Tuscany, named for museum director Georgi Santi.
Intro adapted from Wikipedia (CC BY-SA).
Santite is an IMA-recognized mineral species in the borate class, with the chemical formula KB₅O₆(OH)₄·2H₂O.
It crystallizes in the orthorhombic crystal system (space group Aba2). It is a member of the Santite structural group.
Key properties: specific gravity 1.74; optically biaxial.
IMA symbol Snt, IMA status: approved, named in 1969.
Very rare, formed in fumaroles, probably a product of reaction between potassium-rich solutions and larderellite (Larderello, Italy); as a deposit around a thermal spring (Eagle Borax Spring, California, USA).
It is found associated with Larderellite, sassolite (Larderello, Italy); aristarainite, hydroboracite, kaliborite, mcallisterite, pinnoite, rivadavite (Eagle Borax Spring, California, USA).
The mineral was named to honor Giorgio Santi (1746–1822), Italian chemist and Director, Museum of Natural History, University of Pisa, Pisa, Italy.