Okenite

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Okenite
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General
CategoryPhyllosilicate
Formula
(repeating unit)
CaSi2O5·2H2O
Strunz classification9.EA.40
Crystal systemTriclinic
Crystal classPinacoidal (1)
(same H-M symbol)
Space groupP1
Unit cella = 9.69, b = 7.28
c = 22.02 [Å]; α = 92.7°
β = 100.1°, γ = 110.9°; Z = 2
Identification
ColorWhite, may show slightly yellow or blue tint
Crystal habitBladed crystals, typically fibrous, clusters of curved crystals and radial balls
TwinningLamellar
CleavagePerfect on {001}
FractureSplintery
TenacityElastic
Mohs scale hardness4 12-5
LusterVitreous, pearly
StreakWhite
DiaphaneityTransparent, translucent
Specific gravity2.28 - 2.33
Optical propertiesBiaxial (-)
Refractive indexnα = 1.512 - 1.532 nβ = 1.514 - 1.535 nγ = 1.515 - 1.542
Birefringenceδ = 0.003 - 0.010
2V angleMeasured: 60°
References[1][2][3]

Okenite (CaSi2O5·2H2O)[2] is a silicate mineral that is usually associated with zeolites. It most commonly is found as small white "cotton ball" formations within basalt geodes. These formations are clusters of straight, radiating, fibrous crystals that are both bendable and fragile.[4]

Discovery and occurrence[edit]

It was first described in 1828 for an occurrence at Disko Island, Greenland and named for German naturalist Lorenz Oken (1779–1851).[3]

Minerals associated with okenite include apophyllite, gyrolite, prehnite, chalcedony, goosecreekite and many of the mother zeolites. Okenite is found in India, mainly within the state of Maharashtra. Other localities include Bulla Island, Azerbaijan; Aranga, New Zealand; Chile; Ireland and Bordo Island in the Faroe Islands.[2]

References[edit]

  1. ^ Okenite in the Handbook of Mineralogy
  2. ^ a b c Okenite on Mindat.org
  3. ^ a b Okenite data on Webmineral
  4. ^ "OKENITE (Hydrated Calcium Silicate Hydroxide)". Galleries.com. Retrieved 2013-07-27.