Melanophlogite

Formula: C₂H₁₇O₅^.Si₄₆O₉₂

Origin of name:  From Greek for black and to be burned

Crystal system:  Tetragonal, pseudocubic

Crystal class:  4/m 2/m 2/m

Twinning:  On {201}, penetration

Unit cell: a = 16.79 Å, c = 13.39 Å

Colour:  Colourless, pale yellow to deep reddish brown, turbid white

Diaphaneity: 

Luster:  Vitreous

Habit:  Crystals cubes (pseudocubes), rare; thin crusts or complex intergrown rounded aggregates

Hardness:  6.5 to 7

Specific gravity:  2.005 to 2.052

Cleavage:  None

Tenacity:  Brittle

Streak: 

Synonyms/varieties:

Comments:  SiO₂ containing organic compounds