Tatarskite

Formula: Ca₆Mg₂(SO₄)₂(CO₃)₂Cl₄(OH)₄.7H₂O

Origin of name: for Vitalli Borisovich Tatarskii (1907-), Russian mineralogist, Leningrad University

Crystal system: Orthorhombic

Crystal class: unknown

Twinning:

Unit cell: 

Colour: Colourless to slightly yellowish

Diaphaneity: Transparent

Luster: Vitreous, pearly on cleavage

Habit: Massive, coarsely crystalline, pseudomorph of unknown mineral

Hardness: 2.5

Specific gravity: 2.34

Cleavage: 2; on pinacoids

Tenacity: 

Streak: White

Synonyms/varieties:

Comments:  Soluble in boiling water