Tachyhydrite

Formula: CaMg₂Cl₆.12H₂O

Origin of name: from Greek for quick and water, in allusion to its ready deliquescence.

Crystal system: Hexagonal

Crystal class: 3

Twinning:

Unit cell: a = 10.136, c = 17.318

Colour: , Wax-yellow to honey-yellow, may be colourless

Diaphaneity: Transparent to translucent

Luster: Vitreous-greasy

Habit: massive, rounded masses

Hardness: 2

Specific gravity: 1.67

Cleavage: 1; {1011}

Tenacity: 

Streak: White

Synonyms/varieties:

Comments:  Deliquescent - Crystals absorb water from the air and melt or otherwise deteriorate., Tastes Bitter - Bitter tast e from water soluble Mg or Ca compounds.