Black crystals of the rare mineral katophorite on a contrasting whitish matrix from Monte Somma, Vesuvius, Campania, Italy. Ex Vandenbroucke Museum collection from Waregem, Belgium. — Photo: David Hospital · CC BY-SA 4.0
Katophorite
Katophorite is an IMA-recognized mineral species in the silicate class, with the chemical formula Na(NaCa)(Mg₄Al)(Si₇Al)O₂₂(OH)₂.
It crystallizes in the monoclinic crystal system (space group C2/m). It is a member of the Amphibole structural group.
Key properties: Mohs hardness 5–6; specific gravity 3.2–3.5; Vitreous luster; optically biaxial.
IMA symbol Ktp, IMA status: approved, named in 1894.
Found in alkalic volcanic and plutonic igneous rocks; in blueschist facies jadeitites.
It is found associated with Arfvedsonite, aegirine, nepheline, pyroxenes, eckermannite, chromite.
Its name comes from the Greek for a carrying down, in allusion to its volcanic origin.