Mannardite

Formula:  Ba(Ti₆V₂)O₁₆

Origin of name:  For George Mannard, Canadian mining executive

Crystal system:  Tetragonal

Crystal class:  4/m

Twinning: 

Unit cell: 

Colour:  Jet black

Diaphaneity:  Opaque

Luster:  Crystals prismatic, elongated to 5 mm, deeply striated parallel to elongation

Habit: 

Hardness:  7

Specific gravity:  4.12

Cleavage:  1; {100} good

Tenacity: 

Streak:  White

Synonyms/varieties:

Comments:  Vanadium  analogue of redledgeite