Hopeite

Formula:  Zn₃(PO₄)₂ ^. 4H₂O

Origin of name:  For Charles Hope, Scottish chemist

Crystal system:  Orthorhombic

Crystal class:  2/m 2/m 2/m

Twinning: 

Unit cell: a = 10.61 Ǻ,  b = 18.31 Ǻ, c = 5.031 Ǻ

Colour:  Colourless, white, grayish white, pale yellow

Diaphaneity: 

Luster:  Vitreous, pearly on cleavage

Habit:  Crystals short to long prismatic or tabular, faces often irregular, aggregates or crusts; massive, compact

Hardness:  3.25

Specific gravity:  3.05

Cleavage:  3; {010} perfect, {100} good, {001}poor

Tenacity: 

Streak:  White

Synonyms/varieties:

Comments:  Dimorphous with parahopeite