Eckermannite Mineral Data

Eckermannite Mineral Data +

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General Eckermannite Information

Chemical Formula:

NaNa2(Mg4Al)Si8O22(OH)2

Composition:

Molecular Weight = 803.86 gm

Sodium 8.58 % Na 11.57 % Na₂O

Magnesium 12.09 % Mg 20.06 % MgO

Aluminum 3.36 % Al 6.34 % Al₂O₃

Silicon 27.95 % Si 59.80 % SiO₂

Hydrogen 0.25 % H 2.24 % H₂O

Oxygen 47.77 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Na₃Mg₄Al(Si₈O₂₂)(OH)₂

IMA Status:

Valid Species (Pre-IMA) 1942

Locality:

Link to MinDat.org Location Data.

Eckermannite Image

Images:

Eckermannite

Comments: Dark blue-green prismatic crystalline eckermannite in matrix.
Location: Norra Karr, Granna, Jonkoping, Sweden. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Eckermannite Crystallography

Axial Ratios:

a:b:c =0.5456:1:0.2953

Cell Dimensions:

a = 9.762, b = 17.892, c = 5.284, Z = 2; beta = 103.2° V = 898.53 Den(Calc)= 2.97

Crystal System:

Monoclinic - PrismaticH-M Symbol (2/m) Space Group: C 2/m

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

By Intensity(I/I_o): 3.1(1), 2.71(0.8), 3.4(0.7),

Crystal Structure:

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Raudsepp M , Turnock A C , Hawthorne F C , American Mineralogist , 72 (1987) p.959-964, Characterization of cation ordering in synthetic scandium-fluor-eckermannite,, indium-fluor-eckermannite, and scandium-fluor-nyboite by Rietveld structure, refinement, Sample: FScEC-A3

View Additional jPOWD Structure files for Eckermannite
[1]

Physical Properties of Eckermannite

Cleavage:

[110] Perfect

Color:

Blue green.

Density:

3 - 3.17, Average = 3.08

Diaphaniety:

Translucent

Fracture:

Brittle - Uneven - Very brittle fracture producing uneven fragments.

Hardness:

5-6 - Between Apatite and Orthoclase

Luster:

Vitreous (Glassy)

Streak:

greenish white

Optical Properties of Eckermannite

Gladstone-Dale:

CI meas= 0.006 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= -0.032 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2139,KPDmeas= 0.2059,KC= 0.2072

Optical Data:

Biaxial (-), a=1.612-1.638, b=1.625-1.652, g=1.63-1.654, bire=0.0160-0.0180, 2V(Calc)=40-62, 2V(Meas)=80.

Calculated Properties of Eckermannite

Electron Density:

r_electron=3.07 gm/cc
note: r_Eckermannite=3.09 gm/cc.

Fermion Index

Fermion Index = 0.02537
Boson Index = 0.97463

Photoelectric:

PE_Eckermannite= 1.58 barns/electron
U=PE_Eckermannite x r_electron= 4.85 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Eckermannite is Not Radioactive

Eckermannite Classification

Dana Class:

66.1.3c.6 (66)Inosilicate Double-Width Unbranched Chains, W=2

(66.1)Dana Type

(66.1.3c)Group 4, the sodic amphiboles

66.1.3c.1 Glaucophane []Na2(Mg3Al2)Si8O22(OH)2 C 2/m 2/m

66.1.3c.2 Ferroglaucophane []Na2(Fe3Al2)Si8O22(OH)2 C 2/m 2/m

66.1.3c.3 Crossite? Na2(Mg,Fe)3(Al,Fe)2Si8O22(OH)2 C 2/m 2/m

66.1.3c.4 Magnesioriebeckite []Na2(Mg3Fe2)Si8O22(OH)2 C 2/m 2/m

66.1.3c.5 Riebeckite []Na2(Fe3Fe2)Si8O22(OH)2 C 2/m 2/m

66.1.3c.6 Eckermannite NaNa2(Mg4Al)Si8O22(OH)2 C 2/m 2/m

66.1.3c.7 Ferro-eckermannite NaNa2(Fe4Al)Si8O22(OH)2 C 2/m 2/m

66.1.3c.8 Magnesio-arfvedsonite NaNa2(Mg4Fe)Si8O22(OH)2 C 2/m 2/m

66.1.3c.9 Arfvedsonite NaNa2(Fe4Fe)Si8O22(OH)2 C 2/m 2/m

66.1.3c.9a Fluoro-magnesio-arfvedsonite! NaNa2(Mg,Fe)4Fe[Si8O22](F,OH)2 C 2/m 2/m

66.1.3c.9b Potassicarfvedsonite! KNa2Fe4FeSi8O22(OH)2 C 2/m 2/m

66.1.3c.10 Kozulite NaNa2Mn4(Fe,Al)Si8O22(OH)2 C 2/m 2/m

66.1.3c.11 Nyboite NaNa2(Mg3Al2)Si7AlO22(OH)2 C 2/m 2/m

66.1.3c.11a Ferronyboite! NaNa2(Fe)3Al2(Si7Al)O22(OH)2 C 2/m 2/m

66.1.3c.11b Ferric-ferronyboite! NaNa2(Fe)3(Fe)2(Si7Al)O22(OH)2 C 2/m 2/m

66.1.3c.11c Fluoronyboite! NaNa2(Al2Mg3)(Si7Al)O22(F,OH)2 C 2/m 2/m

66.1.3c.12 Leakeite NaNa2(Mg2Fe2Li)Si8O22(OH)2 C 2/m 2/m

66.1.3c.12a Ferroleakeite! NaNa2(Fe)3(Fe)2Li(Si8O22)(OH)2 C 2/m 2/m

66.1.3c.12b Potassicleakeite! KNa2Mg2Fe2LiSi8O22(OH)2 C 2/m 2/m

66.1.3c.13 Kornite Na(CaNa)Fe4(Al,Fe)Si7AlO22(OH)2 C 2/m 2/m

66.1.3c.14 Ungarettiite NaNa2(Mn2Mn3)Si8O22O2 C 2/m 2/m

66.1.3c.15 Fluoro-ferroleakeite NaNa2(Fe2Fe2Li)Si8O22F2 C 2/m 2/m

66.1.3c.16 Obertiite! NaNa2(Mg3FeTi)Si8O22(O,F,OH)2 C 2/m 2/m

66.1.3c.17 Dellaventuraite! NaNa2(Mg2,Mn,Li,Ti)Si8O22O2 C 2/m 2/m

Strunz Class:

VIII/F.08-70 VIII - Silicates

VIII/F - Inosilicates (chain and band) double chains [Si4O11]6-, Alkali-Amphiboles

VIII/F.08 - Amphibole group, Glaucophane - Riebeckite - Kozulite series

VIII/F.08-10 Glaucophane []Na2(Mg3Al2)Si8O22(OH)2 C 2/m 2/m

VIII/F.08-20 Ferroglaucophane []Na2(Fe3Al2)Si8O22(OH)2 C 2/m 2/m

VIII/F.08-30 Crossite? Na2(Mg,Fe)3(Al,Fe)2Si8O22(OH)2 C 2/m 2/m

VIII/F.08-40 Magnesioriebeckite []Na2(Mg3Fe2)Si8O22(OH)2 C 2/m 2/m

VIII/F.08-50 Riebeckite []Na2(Fe3Fe2)Si8O22(OH)2 C 2/m 2/m

VIII/F.08-56 Fluoronyboite! NaNa2(Al2Mg3)(Si7Al)O22(F,OH)2 C 2/m 2/m

VIII/F.08-60 Nyboite NaNa2(Mg3Al2)Si7AlO22(OH)2 C 2/m 2/m

VIII/F.08-65 Ferronyboite! NaNa2(Fe)3Al2(Si7Al)O22(OH)2 C 2/m 2/m

VIII/F.08-67 Ferric-ferronyboite! NaNa2(Fe)3(Fe)2(Si7Al)O22(OH)2 C 2/m 2/m

VIII/F.08-70 Eckermannite NaNa2(Mg4Al)Si8O22(OH)2 C 2/m 2/m

VIII/F.08-80 Ferro-eckermannite NaNa2(Fe4Al)Si8O22(OH)2 C 2/m 2/m

VIII/F.08-81 Ferripedrizite! NaLi2(Fe2Mg2Li)Si8O22(OH)2 C 2/m 2/m

VIII/F.08-83 Sodic-ferripedrizite! Na(LiNa)(Fe2Mg2Li)Si8O22(OH,F)2 C 2/m 2/m

VIII/F.08-84 Ferroleakeite! NaNa2(Fe)3(Fe)2Li(Si8O22)(OH)2 C 2/m 2/m

VIII/F.08-85 Leakeite NaNa2(Mg2Fe2Li)Si8O22(OH)2 C 2/m 2/m

VIII/F.08-86 Fluoro-ferroleakeite NaNa2(Fe2Fe2Li)Si8O22F2 C 2/m 2/m

VIII/F.08-87 Kornite Na(CaNa)Fe4(Al,Fe)Si7AlO22(OH)2 C 2/m 2/m

VIII/F.08-88 Ungarettiite NaNa2(Mn2Mn3)Si8O22O2 C 2/m 2/m

VIII/F.08-89 Obertiite! NaNa2(Mg3FeTi)Si8O22(O,F,OH)2 C 2/m 2/m

VIII/F.08-90 Magnesio-arfvedsonite NaNa2(Mg4Fe)Si8O22(OH)2 C 2/m 2/m

VIII/F.08-92 Fluoro-magnesio-arfvedsonite! NaNa2(Mg,Fe)4Fe[Si8O22](F,OH)2 C 2/m 2/m

VIII/F.08-95 Sodic-ferri-ferropedrizite! NaLi2(Fe2Fe3)Si8O22(OH)2 C 2/m 2/m

VIII/F.08-100 Arfvedsonite NaNa2(Fe4Fe)Si8O22(OH)2 C 2/m 2/m

VIII/F.08-105 Ferriwhittakerite! Na(NaLi)(Mg2Fe2Li)Si8O22(OH)2 C 2/m 2/m

VIII/F.08-110 Kozulite NaNa2Mn4(Fe,Al)Si8O22(OH)2 C 2/m 2/m

VIII/F.08-112 Potassicleakeite! KNa2Mg2Fe2LiSi8O22(OH)2 C 2/m 2/m

VIII/F.08-125 Dellaventuraite! NaNa2(Mg2,Mn,Li,Ti)Si8O22O2 C 2/m 2/m

VIII/F.08-157 Potassicarfvedsonite! KNa2Fe4FeSi8O22(OH)2 C 2/m 2/m

Other Eckermannite Information

References:

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

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Eckermannite

NaNa2(Mg4Al)Si8O22(OH)2
Dana No: 66.1.3c.6 Strunz No: VIII/F.08-70
Locality:

Notes: