Saponite

Formula: (Ca,Na)_0.3(Mg,Fe)₃(Si,Al)₄O₁₀(OH)_2.nH₂O

Origin of name: from Latin sapo= soap

Crystal system: monoclinic

Crystal class: unknown

Twinning:

Unit cell: a = 5.3 Å, b = 9.2 Å, c = 15 Å (variable, depending on water content), b unknown

Colour: white, may be tinted yellowish, grayish, green, bluish, reddish

Diaphaneity: 

Luster: greasy

Habit: massive, very fine-grained, nodular, veins, cavity filling

Hardness: 1 to 2

Specific gravity: 2.24 to 2.30

Cleavage: 1; {001} perfect

Tenacity: 

Streak: 

Synonyms/varieties: sobotkite (Al-rich variety), thalite

Comments: member of the smectite group (clay)