Vuonnemite

Formula: Na₅Nb₃Ti(Si₂O₇)₃O₂F₂.2Na₃PO₄

Origin of name: after locality Vuonnemi River, Khibina massif, Kola Peninsula, Russia

Crystal system: Triclinic

Crystal class: 1

Twinning:

Unit cell: a = 5.5, b = 7.162, c = 14.45, α = 92.63°, β = 95.33°, γ = 90.6°

Colour: Light yellow, lemon yellow, greenish yellow, white, may have a brownish hue

Diaphaneity: 

Luster: Vitreous, greasy

Habit: plates to 1.8 cm, bladed

Hardness: 2 to 3

Specific gravity: 3.13

Cleavage: 3; {001} perfect, two others less perfect

Tenacity: Brittle

Streak: White

Synonyms/varieties:

Comments:  Fluorescent, SW-UV greenish yellow, LW-UV pale greenish yellow, faint bluish green phosphorescence