Epistilbite Mineral Data

Epistilbite Mineral Data +

General Epistilbite Information

Chemical Formula:

CaAl2Si6O16·5(H2O)

Composition:

Molecular Weight = 608.62 gm

Calcium 6.59 % Ca 9.21 % CaO

Aluminum 8.87 % Al 16.75 % Al₂O₃

Silicon 27.69 % Si 59.23 % SiO₂

Hydrogen 1.66 % H 14.80 % H₂O

Oxygen 55.20 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

CaAl₂Si₆O₁₆·5(H₂O)

Environment:

Alteration product in basalts.

IMA Status:

Valid Species (Pre-IMA) 1826

Locality:

Berufjord, Iceland. Link to MinDat.org Location Data.

Name Origin:

From the Greek epi - "near" and the mineral Stilbite.

Synonym:

ICSD 82770

PDF 39-1381

Epistilbite Image

Images:

Epistilbite Quartz

Comments: White epistilbite cluster 25 mm across on amethyst quartz crystal matrix.
Location: Sawda, Jalgaon, Maharashtra, India. Scale: 10x8x5 cm.
© John Betts - Fine Minerals

Epistilbite Crystallography

Axial Ratios:

a:b:c =0.512:1:0.5755

Cell Dimensions:

a = 9.083, b = 17.738, c = 10.209, Z = 4; alpha = 89.95°, beta = 124.58°, gamma = 90° V = 1,354.23 Den(Calc)= 2.98

Crystal System:

Triclinic - PedialH-M Symbol (1) Space Group: C1

$Help on X Ray Diffraction:$ X Ray Diffraction:

By Intensity(I/I_o): 3.45(1), 3.21(0.9), 8.89(0.9),

Crystal Structure:

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Yang P , Armbruster T , European Journal of Mineralogy , 8 (1996) p.263-271, (010) disorder, partial Si,Al ordering, and Ca distribution, in triclinic (C1) epistilbite, Sample: 293 K, Locality: Gibelsbach, Fiesch (Valais, Switzerland)

View Additional jPOWD Structure files for Epistilbite
[1] [2] [3] [4] [5]

Physical Properties of Epistilbite

Cleavage:

[010] Perfect

Color:

White, Yellowish white, Reddish white, Brownish white.

Density:

2.2 - 2.3, Average = 2.25

Diaphaniety:

Transparent to translucent

Fracture:

Uneven - Flat surfaces (not cleavage) fractured in an uneven pattern.

Habit:

Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline).

Habit:

Spherical - Spherical, rounded aggregates.

Habit:

Twinning Common - Crystals are usually twinned.

Hardness:

4-5 - Fluorite-Apatite

Luminescence:

None.

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Epistilbite

Gladstone-Dale:

CI meas= 0.008 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= 0.251 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1705,KPDmeas= 0.2258,KC= 0.2276

Optical Data:

Biaxial (-), a=1.502, b=1.51, g=1.512, bire=0.0100, 2V(Calc)=52, 2V(Meas)=44. Dispersion relatively strong.

Pleochroism (x):

colorless.

Pleochroism (y):

colorless.

Pleochroism (z):

colorless.

Calculated Properties of Epistilbite

Electron Density:

r_electron=2.28 gm/cc
note: r_Epistilbite=2.25 gm/cc.

Fermion Index

Fermion Index = 0.01328
Boson Index = 0.98672

Photoelectric:

PE_Epistilbite= 2.15 barns/electron
U=PE_Epistilbite x r_electron= 4.91 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Epistilbite is Not Radioactive

Epistilbite Classification

Dana Class:

77.1.6.2 (77)Tectosilicate Zeolite group

(77.1)true zeolites

(77.1.6)Mordenite and related species

77.1.6.1 Mordenite (Ca,Na2,K2)Al2Si10O24·7(H2O) C mc2₁ mm2

77.1.6.2 Epistilbite CaAl2Si6O16·5(H2O) C1 1

77.1.6.3 Maricopaite Pb7Ca2(Si,Al)48O100·32(H2O) Cm2m 2/m 2/m 2/m

77.1.6.4 Dachiardite-Ca (Ca,Na2,K2)5Al10Si38O96·25(H2O) C 2/m 2/m

77.1.6.5 Dachiardite-Na (Na2,Ca,K2)4Al4Si20O48·13(H2O) C 2/m 2/m

77.1.6.6 Ferrierite-Mg (Mg,Na,K)2Mg(Si,Al)18O36·9(H2O) Pnnm 2/m 2/m 2/m

77.1.6.6a Ferrierite-K! (K,Na)2Mg(Si,Al)18O36·9(H2O) Pnnm 2/m 2/m 2/m

77.1.6.6b Ferrierite-Na! (Na,K)2Mg(Si,Al)18O36·9(H2O) P 2₁/n 2/m 2/m 2/m

77.1.6.7 Boggsite NaCa2(Al5Si19O48)·17(H2O) I mma 2/m 2/m 2/m

77.1.6.8 Gottardiite! Na3Mg3Ca5Al19Si117O272·93(H2O) C mca 2/m 2/m 2/m

77.1.6.9 Terranovaite! (Na,Ca)8(Si68Al12)O160-29(H2O) C mcm 2/m 2/m 2/m

77.1.6.10 Mutinaite! Na3Ca4Si85Al11O192·60(H2O) P nma 2/m 2/m 2/m

Strunz Class:

VIII/J.23-70 VIII - Silicates

VIII/J - Tectosilicates (network), with zeolite-structure, Bladed Zeolites

VIII/J.23 - Zeolite group, Ferrierite - Laumontite series

VIII/J.23-06 Heulandite-Na! (Na,Ca)2-3Al3(Al,Si)2Si13O36·12(H2O) C 2/m, Cm, C 2 Mono

VIII/J.23-08 Heulandite-K! (K,Na,Ca)2-3Al3(Al,Si)2Si13O36·12(H2O) C 2/m, Cm, C 2 2/m

VIII/J.23-10 Heulandite-Ca (Ca,Na)2-3Al3(Al,Si)2Si13O36·12(H2O) C 2/m, Cm, C 2 Mono

VIII/J.23-12 Heulandite-Sr! (Sr,Na,Ca)2-3Al3(Al,Si)2Si13O36·12(H2O) C 2/m, Cm, C 2 Mono

VIII/J.23-18 Clinoptilolite-Na! (Na,K,Ca)2-3Al3(Al,Si)2Si13O36·12(H2O) C 2/m, C 2, Cm Mono

VIII/J.23-20 Clinoptilolite-K (Na,K,Ca)2-3Al3(Al,Si)2Si13O36·12(H2O) C 2/m, C 2, Cm Mono

VIII/J.23-22 Clinoptilolite-Ca! (Ca,Na,K)2-3Al3(Al,Si)2Si13O36·12(H2O) C 2/m 2/m

VIII/J.23-26 Stilbite-Na! Na3Ca3[Al8Si28O72]·n(H2O)(n=28-32) C 2/m 2/m

VIII/J.23-30 Stilbite-Ca NaCa4[Al8Si28O72]·n(H2O)(n=28-32) C 2/m 2/m

VIII/J.23-40 Barrerite (Na,K,Ca)2Al2Si7O18·6(H2O) Amma or Ammm 2/m 2/m 2/m

VIII/J.23-50 Stellerite CaAl2Si7O18·7(H2O) F mmm 2/m 2/m 2/m

VIII/J.23-60 Goosecreekite CaAl2Si6O16·5(H2O) P 2₁ 2

VIII/J.23-70 Epistilbite CaAl2Si6O16·5(H2O) C1 1

VIII/J.23-80 Brewsterite-Sr (Sr,Ba)Al4Si12O32·10(H2O) P 2₁/m 2/m

VIII/J.23-90 Brewsterite-Ba! (Ba,Sr)Al2Si6O16·5(H2O) P 2₁/m,P 2₁ Mono

Other Epistilbite Information

References:

NAME( Duda&Rejl90) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Ford32)

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Epistilbite

CaAl2Si6O16·5(H2O)
Dana No: 77.1.6.2 Strunz No: VIII/J.23-70
Locality:

Notes: