Eudidymite Mineral Data
General Eudidymite Information
Chemical Formula:
NaBeSi3O7(OH)
Composition:
Molecular Weight = 245.26 gm
Sodium 9.37 % Na 12.64 % Na2 O
Beryllium 3.67 % Be 10.20 % BeO
Silicon 34.35 % Si 73.49 % SiO2
Hydrogen 0.41 % H 3.67 % H2 O
Oxygen 52.19 % O
______ ______
100.00 % 100.00 % = TOTAL OXIDE
Empirical Formula:
NaBe(Si3 O7 )(OH)
Environment:
A late-stage mineral in alkalic nepheline syenite pegmatites.
IMA Status:
Valid Species (Pre-IMA) 1887
Locality:
Island Ovre-Aro, Langesundfiord, Norway. Link to MinDat.org Location Data.
Name Origin:
From the Greek for well and twinned, in allusion to its common occurrence in twins.
Name Pronunciation:
Eudidymite + Pronunciation
Synonym:
ICSD 26001
PDF 14-201
Eudidymite Image
Images:
Eudidymite Crystallography
Axial Ratios:
a:b:c =1.7127:1:1.8997
Cell Dimensions:
a = 12.64, b = 7.38, c = 14.02, Z = 8; beta = 103.7° V = 1,270.62 Den(Calc)= 2.56
Crystal System:
Monoclinic - Prismatic H-M Symbol (2/m) Space Group: C 2/c
X Ray Diffraction:
By Intensity(I/Io ): 3.163(1), 3.074(0.8), 3.398(0.8),
Physical Properties of Eudidymite
Cleavage:
{001} Good, {551} Good
Color:
Blue, Colorless, Violet, Gray, Yellow.
Density:
2.553
Diaphaneity:
Transparent to translucent
Fracture:
Brittle - Generally displayed by glasses and most non-metallic minerals.
Habit:
Tabular - Form dimensions are thin in one direction.
Habit:
Twinning Common - Crystals are usually twinned.
Hardness:
6 - Orthoclase
Luster:
Vitreous (Glassy)
Streak:
white
Optical Properties of Eudidymite
Gladstone-Dale:
CI meas = -0.003 (Superior) - where the CI = (1-KPDmeas /KC ) CI calc = 0 (Superior) - where the CI = (1-KPDcalc /KC )
KPDcalc = 0.2138,KPDmeas = 0.2144,KC = 0.2138 Ncalc = 1.55
Optical Data:
Biaxial (+), a=1.545, b=1.546, g=1.551, bire=0.0060, 2V(Calc)=50, 2V(Meas)=30. Dispersion r > v distinct.
Pleochroism (x):
colorless.
Pleochroism (y):
colorless.
Pleochroism (z):
colorless.
Calculated Properties of Eudidymite
Electron Density:
Bulk Density (Electron Density)=2.55 gm/cc note: Specific Gravity of Eudidymite =2.56 gm/cc.
Fermion Index:
Fermion Index = 0.05 Boson Index = 0.95
Photoelectric:
PEEudidymite = 1.51 barns/electronU=PEEudidymite x r Electron Density= 3.85 barns/cc.
Radioactivity:
GRapi = 0 (Gamma Ray American Petroleum Institute Units) Eudidymite is Not Radioactive
Eudidymite Classification
Dana Class:
66.03.01.03 (66) Inosilicate Double-Width Unbranched Chains, W=2
(66.03) with chains P>2
(66.03.01) P=3
66.03.01.01 Xonotlite Ca6Si6O17(OH)2 P 2/a 2/m
66.03.01.02 Zorite Na6Ti5[Si12O34](O,OH)5•11(H2O) C mmm 2/m 2/m 2/m
66.03.01.03 Eudidymite NaBeSi3O7(OH) C 2/c 2/m
66.03.01.04 Epididymite NaBeSi3O7(OH) Pnam 2/m 2/m 2/m
66.03.01.05 Yuksporite (Sr,Ba)2K4(Ca,Na)14([],Mn,Fe){(Ti,Nb)4(O,OH)4[Si6O17]2[Si2O7]3}(H2O,OH)n,n~3 P 21 /m 2/m
66.03.01.06 Haineaultite ! (Na,Ca)5Ca(Ti,Nb)5(Si,S)12O34(OH,F)8•5(H2O) C 222 2 2 2
66.03.01.07 Chivruaiite ! Ca4(Ti,Nb)5[(Si6O17)2[(OH,O)5]•13-14H2O C mmm 2/m 2/m 2/m
Strunz Class:
09.DG.60 09 - SILICATES (Germanates)
09.D - Inosilicates* Structural terminology according to Liebau (1985)
09.DG -Inosilicates with 3-periodic single and multiple chains
09.DG.60 Eudidymite NaBeSi3O7(OH) C 2/c 2/m
Other Eudidymite Information
References:
NAME( AntBidBlaNic2) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Ford32)
See Also:
Links to other databases for Eudidymite :
1 - Alkali-Nuts(English)
2 - Alkali-Nuts(Francais)
3 - Am. Min. Crystal Structure Database
4 - Amethyst Galleries' Mineral Gallery
5 - Athena
6 - EUROmin Project
7 - Ecole des Mines de Paris
8 - GeoScienceWorld
9 - Google Images
10 - Google Scholar
11 - Handbook of Mineralogy (MinSocAm)
12 - Handbook of Mineralogy (UofA)
13 - MinDAT
14 - Mineralienatlas (Deutsch)
15 - Online Mineral Museum
16 - QUT Mineral Atlas
17 - Ruff.Info
18 - WWW-MINCRYST
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Eudidymite
NaBeSi3O7(OH)
Dana No: 66.03.01.03 Strunz No: 09.DG.60
Locality:
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