Afwillite

Formula:  Ca₃(SiO₃OH)₂.2H₂O

Origin of name:  for Alpheus Fuller Williams (1874-1953). General manager of DeBeers Consolidated Mines, Kimberley, South Africa.

Crystal system:  Monoclinic

Crystal class:  m

Twinning:

Unit cell: a = 16.278 Å, b = 5.632 Å, c = 13.536 Å, b = 134.9°

Colour:  Colourless or white

Diaphaneity: Transparent to translucent.

Luster:  Vitreous

Habit:  Crystals elongated, tabular; massive, often striated, radial fibrous spherulites

Hardness:  3 to 4.5

Specific gravity:  2.62

Cleavage:  2; {10-1} perfect; {100} good

Tenacity:

Streak:  White

Synonyms/varieties:

Comments: Product of contact metamorphism of limestones