Iowaite

Formula:  Mg₆Fe₂(OH)₁₆Cl₂ ^. 4H₂O

Origin of name:  Locality; Iowa

Crystal system:  Hexagonal

Crystal class:  -3m

Twinning: 

Unit cell: 

Colour:  Bluish green

Diaphaneity: 

Luster:  Greasy

Habit:  Crystals platy to 2 cm

Hardness:  ~ 1.5

Specific gravity:  2.11

Cleavage:  1; {0001} perfect micaceous

Tenacity: 

Streak: 

Synonyms/varieties:

Comments:  Chloride analogue of pyroaurite; on exposure to atmosphere loses water and colour and lightens to whitish green