Ashoverite

Formula:  Zn(OH)₂

Origin of name:  After locality; Milltown, Ashover, Derbyshire, England

Crystal system:  Tetragonal

Crystal class:  4/m 2/m 2/m, -42m or 4mm

Twinning:

Unit cell: a = 6.825 Å, c = 33.36 Å

Colour:  Colourless, white

Diaphaneity: Translucent

Luster:  Dull to vitreous

Habit:  Square plates 0.5 mm across, thin markedly towards the edges, commonly in stellate groups of crystals intersecting at angles of 60-70°

Hardness:

Specific gravity:  3.3

Cleavage:  1; {001} perfect

Tenacity:

Streak:  White

Synonyms/varieties:

Comments:  Trimorphous with sweetite and wülfingite; fluoresces bluish white in SW UV. Found in an oxidised vein in limestone.