Elpidite Mineral Data

Elpidite Mineral Data +

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General Elpidite Information

Chemical Formula:

Na2ZrSi6O15·3(H2O)

Composition:

Molecular Weight = 599.75 gm

Sodium 7.67 % Na 10.33 % Na₂O

Zirconium 15.21 % Zr 20.55 % ZrO₂

Silicon 28.10 % Si 60.11 % SiO₂

Hydrogen 1.01 % H 9.01 % H₂O

Oxygen 48.02 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Na₂ZrSi₆O₁₅·3(H₂O)

IMA Status:

Valid Species (Pre-IMA) 1894

Locality:

Narsarsuk in the Julianehaab district, southern Greenland. Link to MinDat.org Location Data.

Name Origin:

From the Greek "ELPIS" = hope, in allusion to the hope of finding another mineral in the layer

Synonym:

ICSD 10277

PDF 29-1294

Elpidite Image

Images:

Elpidite

Comments: Blocky, intergrown crystals of elpidite.
Location: Narsasuk, Greenland. Scale: Crystal size 2 cm.
© John Veevaert

Elpidite Crystallography

Axial Ratios:

a:b:c =0.5102:1:0.4916

Cell Dimensions:

a = 7.297, b = 14.302, c = 7.032, Z = 2; V = 733.87 Den(Calc)= 2.71

Crystal System:

Orthorhombic - PyramidalH-M Symbol (mm2) Space Group: Pb21m

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

By Intensity(I/I_o): 3.24(1), 7.08(1), 5.11(0.8),

Forms:

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Forms: [ 0 1 0] [ 1 1 0] [ 0 1 1]

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Crystal Structure:

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Cannillo E , Rossi G , Ungaretti L , American Mineralogist , 58 (1973) p.106-109, The crystal structure of elpidite

Physical Properties of Elpidite

Cleavage:

[???] Perfect, [???] Perfect

Color:

Brown, Colorless, Yellow brown, White, Light red.

Density:

2.54

Diaphaniety:

Transparent to translucent

Fracture:

Brittle - Generally displayed by glasses and most non-metallic minerals.

Habit:

Fibrous - Crystals made up of fibers.

Hardness:

7 - Quartz

Luminescence:

Non-fluorescent.

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Elpidite

Gladstone-Dale:

CI meas= -0.131 (Poor) - where the CI = (1-KPDmeas/KC)
CI calc= -0.06 (Fair) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2317,KPDmeas= 0.2472,KC= 0.2187

Optical Data:

Biaxial (+), a=1.56, b=1.65, g=1.674, bire=0.1140

Pleochroism (x):

colorless.

Pleochroism (y):

colorless.

Pleochroism (z):

colorless.

Calculated Properties of Elpidite

Electron Density:

r_electron=2.67 gm/cc
note: r_Elpidite=2.71 gm/cc.

Fermion Index

Fermion Index = 0.03041
Boson Index = 0.96959

Photoelectric:

PE_Elpidite= 21.04 barns/electron
U=PE_Elpidite x r_electron= 56.29 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Elpidite is Not Radioactive

Elpidite Classification

Dana Class:

72.5.4.2 (72)Phyllosilicate Two-Dimensional Infinite Sheets with Other Than Six-Membered Rings

(72.5)with corrugated and complex layers

(72.5.4)Elpidite/armstrongite

72.5.4.1 Armstrongite CaZrSi6O15·3(H2O) C 2 2

72.5.4.2 Elpidite Na2ZrSi6O15·3(H2O) Pb21m mm2

Strunz Class:

VIII/F.23-10 VIII - Silicates

VIII/F - Inosilicates (chain and band) Triplet chains [Si6O15/17]6-/10- and modified triplet bands

VIII/F.23 - Elpidite - Terskite series

VIII/F.23-10 Elpidite Na2ZrSi6O15·3(H2O) Pb21m mm2

VIII/F.23-20 Terskite Na4Zr(H4Si6O18) Pnc2 mm2

Other Elpidite Information

References:

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

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Print or Cut-and-Paste your Elpidite Specimen Label here :

Elpidite

Na2ZrSi6O15·3(H2O)
Dana No: 72.5.4.2 Strunz No: VIII/F.23-10
Locality:

Notes: