Tosudite

Formula: Na_0.5(Al,Mg)₆(Si,Al)₈O₁₈(OH)₁₂.5H₂O

Origin of name: for Toshio Sudo (1911- ), Japanese mineralogist and crystallographer, University of Tokyo, Japan.

Crystal system: Monoclinic

Crystal class: 2

Twinning:

Unit cell: a = 5.17, b = 8.97, c = 24.2, β = 94°

Colour: Colourless, white, dark blue to azure blue, white, yellow, green

Diaphaneity: Semitransparent

Luster: Nonmetallic

Habit: crystals microscopic, in aggregates

Hardness: ~ 1

Specific gravity: 2.83

Cleavage: 1; {00} perfect

Tenacity: 

Streak: White

Synonyms/varieties: Alushtite, chlorite

Comments: A 1: interstratification of chlorite and smectite that is dioctahedral on average.  Hydrothermal alteration product of tuffs, andesites, sediments, and so on.