Mineralogy Database

Tuhualite Mineral Data

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General Tuhualite Information

Help on Chemical  Formula: Chemical Formula: [ ](Na,K)Fe++Fe+++[Si6O15]
Help on Composition: Composition: Molecular Weight = 546.41 gm
   Potassium   1.43 %  K     1.72 % K2O
   Sodium      3.37 %  Na    4.54 % Na2O
   Iron       20.44 %  Fe   13.15 % FeO / 14.61 % Fe2O3
   Silicon    30.84 %  Si   65.98 % SiO2
   Oxygen     43.92 %  O
             ______        ______ 
             100.00 %      100.00 % = TOTAL OXIDE
Help on Empirical Formula: Empirical Formula: Na0.8K0.2Fe2+Fe3+Si6O15
Help on Environment: Environment: In volcanic rock.
Help on IMA Status: IMA Status: Valid Species (Pre-IMA) 1932
Help on Locality: Locality: Mayor (Tuhua) Island, Bay of Plenty (Opo Bay), Norht Island, New Zealand. Link to MinDat.org Location Data.
Help on Name Origin: Name Origin: Named for the locality.
Help on Name Pronunciation: Name Pronunciation: Tuhualite + Pronunciation Say TUHUALITE
Help on Synonym: Synonym: ICSD 17017
  PDF 10-440

Tuhualite Image

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Comments: Black, tabular crystals of tuhualite on matrix.
Location: Opo Bay, Mayor Island, New Zealand. Scale: Not Given.
© Lou Perloff / Photo Atlas of Minerals

Tuhualite Crystallography

Help on Axial Ratios: Axial Ratios: a:b:c =0.8281:1:0.585
Help on Cell Dimensions: Cell Dimensions: a = 14.31, b = 17.28, c = 10.11, Z = 8; V = 2,499.97 Den(Calc)= 2.90
Help on Crystal System: Crystal System: Orthorhombic - Dipyramidal H-M Symbol (2/m 2/m 2/m) Space Group: C mca
Help on X Ray Diffraction: X Ray Diffraction: By Intensity(I/Io): 7.16(1), 2.77(0.9), 3.18(0.8),

Physical Properties of Tuhualite

Help on Cleavage: Cleavage: {100} Good, {010} Good, {001} Good
Help on Color: Color: Blue violet, Dark blue, Black.
Help on Density: Density: 2.89
Help on Fracture: Fracture: Brittle - Generally displayed by glasses and most non-metallic minerals.
Help on Hardness: Hardness: 3-4 - Calcite-Fluorite
Help on Streak: Streak: reddish gray

Optical Properties of Tuhualite

Help on Gladstone-Dale: Gladstone-Dale: CI meas= 0.035 (Excellent) - where the CI = (1-KPDmeas/KC)
CI calc= 0.038 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2116,KPDmeas= 0.2123,KC= 0.22
Ncalc = 1.64
Help on Optical Data: Optical Data: Biaxial (+), a=1.608, b=1.612, g=1.621, bire=0.0130, 2V(Calc)=68, 2V(Meas)=61-70.
Help on Pleochroism (x): Pleochroism (x): deep purple.
Help on Pleochroism (y): Pleochroism (y): violet.
Help on Pleochroism (z): Pleochroism (z): pale pink.

Calculated Properties of Tuhualite

Help on Electron Density: Electron Density: Bulk Density (Electron Density)=2.84 gm/cc
note: Specific Gravity of Tuhualite =2.89 gm/cc.
Help on Fermion Index: Fermion Index: Fermion Index = 0.01
Boson Index = 0.99
Help on Photoelectric: Photoelectric: PETuhualite = 7.44 barns/electron
U=PETuhualite x relectron= 21.14 barns/cc.
Help on Radioactivity: Radioactivity:

GRapi = 20.32 (Gamma Ray American Petroleum Institute Units)
Concentration of Tuhualite per GRapi unit = 4.92 (%)

Estimated Radioactivity from Tuhualite - barely detectable


Tuhualite Classification

Help on  Dana Class: Dana Class: (66)Inosilicate Double-Width Unbranched Chains, W=2
  (66.03)with chains P>2
  (66.03.04)P=6 (Tahualite group) Tuhualite [](Na,K)FeFe[Si6O15] C mca 2/m 2/m 2/m Zektzerite NaLiZrSi6O15 C mca 2/m 2/m 2/m Emeleusite Na4Li2Fe2Si12O30 Pnna 2/m 2/m 2/m
Help on  Strunz Class: Strunz Class: 09.DN.05 09 - SILICATES (Germanates)
  09.D - Inosilicates* Structural terminology according to Liebau (1985)
  09.DN -Inosilicates with 6-periodic double chains
09.DN.05 Emeleusite Na4Li2Fe2Si12O30 Pnna 2/m 2/m 2/m
09.DN.05 Tuhualite [](Na,K)FeFe[Si6O15] C mca 2/m 2/m 2/m
09.DN.05 Zektzerite NaLiZrSi6O15 C mca 2/m 2/m 2/m

Other Tuhualite Information

Help on References: References: NAME( Dana8) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)
Help on See Also: See Also: Links to other databases for Tuhualite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - EUROmin Project
4 - Ecole des Mines de Paris
5 - GeoScienceWorld
6 - Google Images
7 - Google Scholar
8 - Handbook of Mineralogy (MinSocAm)
9 - Handbook of Mineralogy (UofA)
10 - MinDAT
11 - Mineralienatlas (Deutsch)
12 - Online Mineral Museum
13 - QUT Mineral Atlas
14 - Ruff.Info

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[ ](Na,K)Fe++Fe+++[Si6O15]
Dana No: Strunz No: 09.DN.05





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