Vlasovite

Formula: Na₂ZrSi₄O₁₁

Origin of name: for Russian mineralogist and geochemist Kuz'ma Alekseevich Vlasov (1905{1964), founder of the Institute of Mineralogy, Geochemistry, and Crystal Chemistry of Rare Elements, Moscow, Russia.

Crystal system: Monoclinic

Crystal class: 2/m

Twinning: Uncommon, twin plane {010}

Unit cell: a = 10.98, b = 10, c = 8.52, β = 100.4°

Colour: Colourless, pink, pale brown, silvery

Diaphaneity: Transparent

Luster: Greasy, vitreous to pearly on cleavage

Habit: grains to 1.5 cm

Hardness: 6

Specific gravity: 2.97

Cleavage: 2; {010} distinct, {h0l} at 88° imperfect

Tenacity: Brittle, uneven to conchoidal fracture

Streak: White

Synonyms/varieties:

Comments: also triclinic, altered material fluoresces strong orange-yellow under SW-UV