Richterite

Formula: Na(Ca,Na)(Mg,Fe)₅Si₈O₂₂(OH,F)₂

Origin of name: for Theodor Richter, Geman mineralogist

Crystal system: monoclinic

Crystal class: 2/m

Twinning: 

Unit cell: 

Colour: brown, yellow, brownish red, rose-red, pale to dark green

Diaphaneity: transparent to translucent

Luster: vitreous

Habit: crystals long prismatic, rarely terminated

Hardness: 5 to 6

Specific gravity: 2.97 to 3.132

Cleavage: 3; {110} perfect, {001} and {100} parting

Tenacity: 

Streak: 

Synonyms/varieties:

Comments: member of the amphibole group, series with ferrorichterite