Umbrianite
Umbrianite is an IMA-recognized mineral species in the silicate class, with the chemical formula K₇Na₂Ca₂[Al₃Si₁₀O₂₉]F₂Cl₂.
It crystallizes in the orthorhombic crystal system (space group Pmmn).
Key properties: Mohs hardness 5; specific gravity 2.49; White streak; Vitreous luster; optically biaxial.
IMA symbol Ubn, IMA status: approved, named in 2011.
Essential groundmass, late-magmatic mineral in vesicular melilitolite, unstable under post-magmatic hydrothermal conditions and alters to Ba-rich hydrated phases.
It is found associated with Kalsilite, leucite, fluorophlogopite, melilite, olivine (Fo 60), diopside, nepheline, Ti-rich magnetite, fluorapatite, cuspidine-hiortdahlite series minerals.
The name refers to Umbria, the region of Central Italy where the studied material was collected.