Apjohnite

Formula:  MnAl₂(SO₄)₄^.22H₂O

Origin of name:  For James Apjohn, Irish mineralogist and chemist

Crystal system:  Monoclinic

Crystal class:  2/m

Twinning:

Unit cell: a = 6.198 Å, b = 24.347 Å, c = 21.266 Å, b = 100.28°

Colour:  Colourless, white, pale shades of yellow, green, pink

Diaphaneity: Transparent

Luster:  Silky

Habit:  Masses, crusts of fibrous or acicular crystals

Hardness:  1.5

Specific gravity:  1.81

Cleavage:  None

Tenacity:

Streak: White

Synonyms/varieties:

Comments: