Mineral - Afwillite
Afwillite
Chemical Properties
Mineral Class
Silicates
Toxicity
none
Formula
Ca₃(HSiO₄)₂ · 2H₂O
Unit Cell
a=16.28 b=5.63 c=13.24 β=135° Z=4
Physical Properties
Hardness
3 - 4
Streak
white
Density
Normal (2-3,5)
Cleavage
Perfect after (10 1 ), good after (100)
Fracture
conchoidal
Tenacity
Brittle
Optical Properties
Color
whiteturquoiseblue whitecolorless
Birefringence
0.017
Luster
Vitreous
Transparency
transparent
Pleochroism
Geomineralogical Properties
Crystal System
monoclinic
Point Group
monoclinic-domatic - m
Space Group
Cc (9)
Habit
blocky, acicular, prismatic, spear-shaped, tabular
Formation
Formed by low-temperature hydrothermal alteration or hydration of primary calcium silicates in contact-metamorphosed calcareous rocks
Paragenesis
Twinning
Rarity
Rare
Synonyms
Afwillite
Composition
Elements
Mass
SiO₂
33.96
(Al,Fe)₂O₃
0.60
CaO
49.28
H₂O
16.01
South Africa (Parry & Wright 1925)
Name and first discovery : Named in 1925 by John Parry and Frederick Eugene Wright in honor of Alpheus Fuller Williams (1874-1953) of De Beers.
Chemistry :
Synonyms :
Varieties :
Abbreviation : Afw
literature
Parry, J., & Wright, F. E. (1925). Afwillite, a new hydrous calcium silicate, from Dutoitspan Mine, Kimberley, South Africa. Mineralogical magazine and journal of the Mineralogical Society , 20 (108), 277-286.