Arupite

Formula:  Ni₃(PO₄)₂^.8H₂O

Origin of name:  For Hans Arup (1928- ), Director of the Danish Corrosion Centre, Copenhagen, Denmark

Crystal system:  Monoclinic

Crystal class:  2/m

Twinning:

Unit cell: a = 9.889 Å, b = 13.225 Å, c = 4.645 Å, b = 102.41°

Colour:  Sky-blue to turquoise-blue

Diaphaneity: Translucent

Luster:  Earthy, dull

Habit:  Short prismatic grains 2-5 um forming aggregates to 2 mm across

Hardness:  1.5 to 2

Specific gravity: 2.85 (calculated)

Cleavage: 1; good

Tenacity:

Streak: Light blue

Synonyms/varieties:

Comments:  Ni analogue of vivianite. Member of the vivianite group.  Found as a weathering product of a nickel-rich iron meteorite.