Epididymite Mineral Data

Epididymite Mineral Data +

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General Epididymite Information

Chemical Formula:

NaBeSi3O7(OH)

Composition:

Molecular Weight = 245.26 gm

Sodium 9.37 % Na 12.64 % Na₂O

Beryllium 3.67 % Be 10.20 % BeO

Silicon 34.35 % Si 73.49 % SiO₂

Hydrogen 0.41 % H 3.67 % H₂O

Oxygen 52.19 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

NaBe(Si₃O₇)(OH)

IMA Status:

Valid Species (Pre-IMA) 1893

Locality:

Island of Aro, Langesundfiord, Norway. Link to MinDat.org Location Data.

Name Origin:

From the Greek epi, "near" and didymos, "twin", for its dimorphous relationship with eudidymite

Synonym:

ICSD 2941

PDF 14-64

Epididymite Image

Images:

Epididymite

Comments: Trilling twinned crystal of epididymite on matrix.
Location: Mont St. Hilaire, Quebec, Canada. Scale: Not Given.
© Lou Perloff / Photo Atlas of Minerals

Images:

Epididymite Eudidymite

Comments: Translucent prismatic crystals of eudidymite on white opaque epididymite.
Location: Narsaarsuk, Greenland. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Epididymite Crystallography

Axial Ratios:

a:b:c =1.7247:1:1.8365

Cell Dimensions:

a = 12.66, b = 7.34, c = 13.48, Z = 8; V = 1,252.62 Den(Calc)= 2.60

Crystal System:

Orthorhombic - DipyramidalH-M Symbol (2/m 2/m 2/m) Space Group: Pnam

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

By Intensity(I/I_o): 2.99(1), 3.09(1), 3.4(1),

Crystal Structure:

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Robinson P D , Fang J H , American Mineralogist , 55 (1970) p.1541-1549, The crystal structure of epididymite

Physical Properties of Epididymite

Cleavage:

[001] Perfect, [010] Perfect

Color:

Colorless, White, Gray, Yellow, Blue.

Density:

2.55

Diaphaniety:

Transparent to translucent

Fracture:

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

Hardness:

5.5 - Knife Blade

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Epididymite

Gladstone-Dale:

CI meas= 0.001 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= 0.02 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2095,KPDmeas= 0.2136,KC= 0.2138

Optical Data:

Biaxial (+), a=1.544, b=1.544, g=1.546, bire=0.0020, 2V(Calc)=0, 2V(Meas)=22.

Calculated Properties of Epididymite

Electron Density:

r_electron=2.54 gm/cc
note: r_Epididymite=2.55 gm/cc.

Fermion Index

Fermion Index = 0.05303
Boson Index = 0.94697

Photoelectric:

PE_Epididymite= 1.51 barns/electron
U=PE_Epididymite x r_electron= 3.84 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Epididymite is Not Radioactive

Epididymite Classification

Dana Class:

66.3.1.4 (66)Inosilicate Double-Width Unbranched Chains, W=2

(66.3)with chains P>2

(66.3.1)P=3

66.3.1.1 Xonotlite Ca6Si6O17(OH)2 P 2/a 2/m

66.3.1.2 Zorite Na6Ti5[Si12O34](O,OH)5·11(H2O) C mmm 2/m 2/m 2/m

66.3.1.3 Eudidymite NaBeSi3O7(OH) C 2/c 2/m

66.3.1.4 Epididymite NaBeSi3O7(OH) Pnam 2/m 2/m 2/m

66.3.1.5 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

66.3.1.6 Haineaultite! (Na,Ca)5Ca(Ti,Nb)5(Si,S)12O34(OH,F)8·5(H2O) C 222 2 2 2

66.3.1.7 IMA2004-052! Ca3Ti5[(Si6O17)2|O(OH)4]·14(H2O) C mmm 2/m 2/m 2/m

Strunz Class:

VIII/G.04-20 VIII - Silicates

VIII/G - Intermediate between chain- and layered silicates

VIII/G.04 - Eudidymite - Epididymite series

VIII/G.04-10 Eudidymite NaBeSi3O7(OH) C 2/c 2/m

VIII/G.04-20 Epididymite NaBeSi3O7(OH) Pnam 2/m 2/m 2/m

Other Epididymite Information

References:

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

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Epididymite

NaBeSi3O7(OH)
Dana No: 66.3.1.4 Strunz No: VIII/G.04-20
Locality:

Notes: