Borax

Formula:  Na₂B₄O₅(OH)₄ ^. 8H₂O

Origin of name:  From Persian burah - white

Crystal system:  Monoclinic

Crystal class:  2/m

Twinning:  Rare on {100}

Unit cell: a = 12.22 Ǻ, b = 10.67 Ǻ, c = 11.88 Ǻ, β = 106.6˚

Colour:  Colourless, white, grayish, greenish, bluish

Diaphaneity:  Transparent

Luster:  Vitreous, sometimes earthy

Habit:  Crystals short prismatic, somewhat tabular

Hardness:  2 to 2.5

Specific gravity:  1.715

Cleavage:  2; {100} perfect, {110} imperfect

Tenacity:

Streak:

Synonyms/varieties:  Tincal

Comments:  Soluble in water