Averievite

Formula: Cu₅O₂(VO₄)₂.CuCl₂.(Cs, K, Rb)Cl

Origin of name: After Valerii Viktorovich Aver'ev (Averiev) (1929-1968), volcanologist, Institute of Volcanology, Petropavlovsk-Kamchatskii, Russia

Crystal system: Hexagonal

Crystal class: 3

Twinning:

Unit cell: a = 6.375 Å, c = 8.399 Å

Colour: Black

Diaphaneity: Opaque

Luster: Metallic to resinous

Habit: Pseudo-hexagonal crystals

Hardness: About 4

Specific gravity: 3.54 (thought low due to adhesion of air bubbles), 4.01 (calculated)

Cleavage: 1; On {10-10} good

Tenacity: Brittle

Streak: Black

Synonyms/varieties:

Comments: Found in volcanic fumaroles. Related to stoiberite