Afwillite

Afwillite is a calcium hydroxide nesosilicate mineral with formula Ca3Si2O4(OH)6. It occurs as glassy, colorless to white prismatic monoclinic crystals. Its Mohs scale rating is 4.5. It occurs as an alteration mineral in contact metamorphism of limestone. It was first described in 1925 for an occurrence in the Dutoitspan Mine, Kimberley, South Africa and was named for Alpheus Fuller Williams (1874-1953), a past official of the De Beers diamond company.
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General Information:
 Chemical Formula:
Ca3Si2O4(OH)6
 Composition:
(Molecular Weight = 342.45 gm)
Calcium 35.11 % Ca
Silicon 16.40 % Si
Hydrogen 1.77 % H 
Oxygen 46.72 % O 
 Empirical Formula:
Ca3(Si2O4)(OH)6
 Environment:
Alteration product of spurrite.
 Locality:
TL: Dutoitspan diamond mine at Kimberly, South Africa.
Physical Properties:
 Cleavage:
[001] Perfect, [???] Distinct
 Color:
colorless or white.
 Density:
2.62
 Diaphaniety:
Transparent to Subtransparent to translucent
 Habits:
Massive - Uniformly indistinguishable crystals forming large masses., Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline).,
 Hardness:
3 - Calcite
 Luster:
Vitreous (Glassy)
 Streak:
white
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AFWILLITE

B: (Kimia) kalsium silikat terhidrasi; afwilit
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