Tuhualite Mineral Data

General Tuhualite Information

Chemical Formula:

[ ](Na,K)Fe++Fe+++[Si6O15]

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

Empirical Formula:

Na_0.8K_0.2Fe²⁺Fe³⁺Si₆O₁₅

Environment:

In volcanic rock.

IMA Status:

Valid Species (Pre-IMA) 1932

Locality:

Mayor (Tuhua) Island, Bay of Plenty (Opo Bay), Norht Island, New Zealand. Link to MinDat.org Location Data.

Name Origin:

Named for the locality.

Name Pronunciation:

Tuhualite + Pronunciation

Synonym:

ICSD 17017

PDF 10-440

Tuhualite Image

Images:

Tuhualite

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

Axial Ratios:

a:b:c =0.8281:1:0.585

Cell Dimensions:

a = 14.31, b = 17.28, c = 10.11, Z = 8; V = 2,499.97 Den(Calc)= 2.90

Crystal System:

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

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

By Intensity(I/I_o): 7.16(1), 2.77(0.9), 3.18(0.8),

Crystal Structure:

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Merlino S , Science , 166 (1969) p.1399-1401, Tuhualite crystal structure, Locality: Mayor Island, New Zealand, Note: Position of H2O not determined in paper

Physical Properties of Tuhualite

Cleavage:

{100} Good, {010} Good, {001} Good

Color:

Blue violet, Dark blue, Black.

Density:

2.89

Fracture:

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

Hardness:

3-4 - Calcite-Fluorite

Streak:

reddish gray

Optical Properties of Tuhualite

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

Optical Data:

Biaxial (+), a=1.608, b=1.612, g=1.621, bire=0.0130, 2V(Calc)=68, 2V(Meas)=61-70.

Pleochroism (x):

deep purple.

Pleochroism (y):

violet.

Pleochroism (z):

pale pink.

Calculated Properties of Tuhualite

Electron Density:

Bulk Density (Electron Density)=2.84 gm/cc
note: Specific Gravity of Tuhualite =2.89 gm/cc.

Fermion Index:

Fermion Index = 0.01
Boson Index = 0.99

Photoelectric:

PE_Tuhualite= 7.44 barns/electron
U=PE_Tuhualite x r_electron= 21.14 barns/cc.

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

Dana Class:

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

(66.03)with chains P>2

(66.03.04)P=6 (Tahualite group)

66.03.04.01 Tuhualite [](Na,K)FeFe[Si6O15] C mca 2/m 2/m 2/m

66.03.04.02 Zektzerite NaLiZrSi6O15 C mca 2/m 2/m 2/m

66.03.04.03 Emeleusite Na4Li2Fe2Si12O30 Pnna 2/m 2/m 2/m

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

References:

NAME( Dana8) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)

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
15 - WWW-MINCRYST

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Ask about Tuhualite here :
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Print or Cut-and-Paste your Tuhualite Specimen Label here :

Tuhualite

[ ](Na,K)Fe++Fe+++[Si6O15]
Dana No: 66.03.04.01 Strunz No: 09.DN.05
Locality:

Notes: