Vanthoffite

Formula: Na₆Mg(SO₄)₄

Origin of name: for for Jacobus Hendricus van't Hoff (1852-1911), Dutch physical chemist.

Crystal system: Monoclinic

Crystal class: 2/m

Twinning:

Unit cell: a = 9.8, b = 9.22, c = 8.2, β = 113.5°

Colour: Colourless, gray, pale yellow

Diaphaneity: Transparent

Luster: Vitreous to pearly

Habit: anhedral grains, bedded aggregates, massive

Hardness: 3.5

Specific gravity: 2.694

Cleavage: None

Tenacity: Friable, conchoidal, uneven fracture

Streak: White

Synonyms/varieties:

Comments:  Soluble in water, slightly bitter taste