Gaultite

Formula:  Na₄Zn₂Si₇O₁₈ ^. 5H₂O

Origin of name:  For Robert A. Gault, Canadian mineralogist

Crystal system:  Orthorhombic

Crystal class:  mm2

Twinning:

Unit cell:

Colour:  Colourless to pale purple

Diaphaneity:  Transparent

Luster:  Vitreous

Habit:  Euhedral crystals to 0.5 mm

Hardness:  6

Specific gravity:  2.52

Cleavage:  3; {101} and {010} perfect, {021} poor

Tenacity:

Streak:  White

Synonyms/varieties:

Comments:  Fluoresces bright apple green in SW UV; slowly soluble in 1:1 HCl