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Tuhualite

Formula:
(Na,K)
 
2
Fe
 
2
Fe
 
2
Si
 
12
O
 
30
·H
 
2
O
System:OrthorhombicColour:Dark blue to black
Name:From the Maori "Tuhua", the original name for Mayor Island, New Zealand.


Tuhualite Group.

Classification of Tuhualite

IMA status:Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
Strunz 8th edition ID:8/F.30-20
Nickel-Strunz 10th (pending) edition ID:9.DN.05

9 : SILICATES (Germanates)
D : Inosilicates
N : Inosilicates with 6-periodic double chains
Dana 8th edition ID:66.3.4.1

66 : INOSILICATES Double-Width,Unbranched Chains,(W=2)
3 : Amphiboles - Ca-Na subgroup
Hey's CIM Ref.:16.18.3

16 : Silicates Containing Aluminum and other Metals
18 : Aluminosilicates of Fe and alkalis
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Type Occurrence of Tuhualite

Type Locality:Mayor Island (Tuhua), New Zealand
Year of Discovery:1932

Physical Properties of Tuhualite

Colour:Dark blue to black
Tenacity:Brittle

Crystallography of Tuhualite

Crystal System:Orthorhombic
Cell Parameters:a = 14.31Å, b = 17.28Å, c = 10.11Å
Ratio:a:b:c = 0.828 : 1 : 0.585
Unit Cell Volume:V 2,499.97 ų (Calculated from Unit Cell)

Optical Data of Tuhualite

Type:Biaxial (+)
RI values: nα = 1.608 nβ = 1.612 nγ = 1.621
2V:Measured: 61° to 70°, Calculated: 68°
Maximum Birefringence:δ = 0.013

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:Moderate
Dispersion:r < v

Chemical Properties of Tuhualite

Formula:
(Na,K)
 
2
Fe
 
2
Fe
 
2
Si
 
12
O
 
30
·H
 
2
O
Essential elements:Fe, H, Na, O, Si
All elements listed in formula:Fe, H, K, Na, O, Si
Common Impurities:Ti,Zr,Al,Mn,Mg,Ca,F,Cl,H2O

Relationship of Tuhualite to other Species

Related to:
  • Tuhualite Group
  • Related Minerals - Nickel-Strunz Grouping):
    9.DN.05Emeleusite
    Li
     
    2
    Na
     
    4
    Fe
     
    2
    Si
     
    12
    O
     
    30
    9.DN.05Zektzerite
    LiNa(Zr,Ti,Hf)Si
     
    6
    O
     
    15
    9.DN.10Semenovite-(Ce)
    (Na,Ca)
     
    9
    Fe
    2+
     
    (Ce,La)
     
    2
    [(Si,Be)
     
    5
    (O,OH,F)
     
    12
    ]
     
    4
    9.DN.15Ashcroftine-(Y)
    K
     
    5
    Na
     
    5
    (Y,Ca)
     
    12
    Si
     
    28
    O
     
    70
    (OH)
     
    2
    (CO
     
    3
    )
     
    8
    ·8H
     
    2
    O
    Related Minerals - Hey's Index Grouping:
    16.18.1Nontronite
    Na
     
    0.3
    Fe
     
    2
    (Si,Al)
     
    4
    O
     
    10
    (OH)
     
    2
    ·nH
     
    2
    O
    16.18.2Ferroglaucophane
    [ ][Na
     
    2
    ][Fe
    2+
    3
    Al
     
    2
    ][(OH)
     
    2
    |Si
     
    8
    O
     
    22
    ]
    16.18.4Annite
    KFe
    2+
    3
    [(OH)
     
    2
    |AlSi
     
    3
    O
     
    10
    ]
    16.18.5Siderophyllite
    KFe
    2+
    2
    Al[(F,OH)
     
    2
    |Al
     
    2
    Si
     
    2
    O
     
    10
    ]

    Other Names for Tuhualite

    German names:
    Tuhualit
    Russian names:
    Тухуалит
    Spanish names:
    Tuhualita

    Other Information

    Health Warning:No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

    References for Tuhualite

    Reference List:New Zealand Journal Sci. Techn. (1932): 13: 198-202.

    American Mineralogist (1956): 41: 959.

    Mineralogical Magazine (1956): 31: 96-106.

    Science (1969): 166: 1399-1401.

    Articles/Blogs about Tuhualite

    Internet Links for Tuhualite

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  • Raman and XRD data at RRUFF project
  • American Mineralogist Crystal Structure Database
  • Search for Tuhualite in the Natural History Museum (London) online catalogue
  • Tuhualite details from Handbook of Mineralogy (PDF)
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    Localities for Tuhualite

    The map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.
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    (TL) indicates type locality. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
    New Zealand
     
    New Zealand J.Sci.Techn.(1932) 13, 198-202
    NZJGG, 2003, 46: 581-590. NZJGG, 1991, 34: 337-340. NZJGG, 1981, 24: 449-467
    NZJGG, 2003, 46: 581-590. NZJGG, 1991, 34: 337-340. NZJGG, 1981, 24: 449-467
    NZJGG, 2003, 46: 581-590. NZJGG, 1991, 34: 337-340. NZJGG, 1981, 24: 449-467
    Tajikistan
     
    • Region of Republican Subordination
      • Tien Shan Mts
        • Alayskiy (Alai) Range
    L.A. Pautov data
    Mineral and/or Locality
    Google
     
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