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About TuhualiteHide

Na may be replaced by minor K.
Dark blue to black
Specific Gravity:
Crystal System:
Member of:
From the Maori "Tuhua" (obsidian), the original name for Mayor Island, New Zealand.

Classification of TuhualiteHide

Approved, 'Grandfathered' (first described prior to 1959)

9 : SILICATES (Germanates)
D : Inosilicates
N : Inosilicates with 6-periodic double chains

66 : INOSILICATES Double-Width,Unbranched Chains,(W=2)
3 : Amphiboles - Ca-Na subgroup

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

Physical Properties of TuhualiteHide

Dark blue to black
Very brittle
Three good on (001), (010), (100)
2.89(2) g/cm3 (Measured)    

Optical Data of TuhualiteHide

Biaxial (+)
RI values:
nα = 1.608 nβ = 1.612 nγ = 1.621
Measured: 61° to 70°, Calculated: 68°
Max Birefringence:
δ = 0.013
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
r < v
a = colourless to pale lavender, b = violet, lavender, c = intense purplish-blue

Chemical Properties of TuhualiteHide


Na may be replaced by minor K.
Common Impurities:

Crystallography of TuhualiteHide

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

Type Occurrence of TuhualiteHide

Geological Setting of Type Material:
in rhyolites
Associated Minerals at Type Locality:

Other Language Names for TuhualiteHide


Relationship of Tuhualite to other SpeciesHide

Member of:
Other Members of this group:

Common AssociatesHide

Associated Minerals Based on Photo Data:
1 photo of Tuhualite associated with SogdianiteK(□,Na)2Li3(Zr,Fe,Ti)2[Si12O30]
1 photo of Tuhualite associated with PolylithioniteKLi2Al(Si4O10)(F,OH)2
1 photo of Tuhualite associated with QuartzSiO2
1 photo of Tuhualite associated with AegirineNaFe3+Si2O6

Related Minerals - Nickel-Strunz GroupingHide

9.DN.10Semenovite-(Ce)Na8Ca2FeBe6Ce2Si14O40(OH)4F4Orth. mmm (2/m 2/m 2/m)
9.DN.15Ashcroftine-(Y)K5Na5(Y,Ca)12Si28O70(OH)2(CO3)8 · 8H2OTet. 4/mmm (4/m 2/m 2/m) : I4/mmm

Related Minerals - Dana Grouping (8th Ed.)Hide

Related Minerals - Hey's Chemical Index of Minerals GroupingHide

16.18.1NontroniteNa0.3Fe2((Si,Al)4O10)(OH)2 · nH2OMon.
16.18.4AnniteKFe2+3(AlSi3O10)(OH)2Mon. 2/m : B2/m

Other InformationHide

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

References for TuhualiteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Marshall, P. (1932) Notes on some volcanic rocks of the North Island of New Zealand. The New Zealand Journal of Science and Technology: 13: 198-202.
Foshag, W.F. (1933) New mineral names. American Mineralogist: 18: 179-180.
Marshall, P. (1937) The mineral tuhualite. Transactions and Proceedings of the New Zealand Institute: 66: 330-336.
Foshag, W.F. (1937) New mineral names. American Mineralogist: 22: 1131-1132.
Fleischer, M. (1956) New mineral names. American Mineralogist: 41: 958-960.
Hutton, C.O. (1956) Re-examination of the mineral tuhualite. Mineralogical Magazine, 31:96–106.
Merlino, S. (1969) Tuhualite crystal structure. Science: 166: 1399-1401.
Taran, M. N., & Rossman, G. R. (2001). Optical spectroscopic study of tuhualite and a re-examination of the beryl, cordierite, and osumilite spectra. American Mineralogist, 86(9), 973-980.
Merlino, S., Biagioni, C. (2018): Tuhualite revisited: new crystal data and structure refinements on specimens from two localities. Periodico die Mineralogia 87, 257-267.

Internet Links for TuhualiteHide

Localities for TuhualiteHide

This 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.

Locality ListHide

- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for further information on this occurrence. ? - Indicates mineral may be doubtful at this locality. - Good crystals or important locality for species. - World class for species or very significant. (TL) - Type Locality for a valid mineral species. (FRL) - First Recorded Locality for everything else (eg varieties). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (eg from pseudomorphs.)

All localities listed without proper references should be considered as questionable.
  • Sicily
    • Trapani Province
Bagiński, B., Macdonald, R., White, J. C., & Jeżak, L. (2018). Tuhualite in a peralkaline rhyolitic ignimbrite from Pantelleria, Italy. European Journal of Mineralogy.
  • Hovd Aimag (Khovd Aimag)
    • Altai Mts
Irina A. Andreeva data; Andreeva, I. A. (2016). Genesis and mechanisms of formation of rare-metal peralkaline granites of the Khaldzan Buregtey massif, Mongolia: Evidence from melt inclusions. Petrology, 24(5), 462-476.
New Zealand (TL)
  • Bay of Plenty Region
New Zealand J.Sci.Techn.(1932) 13, 198-202. Osborne Hutton, C. (1956) Re-Examination of the mineral tuhualite. Mineralogical Magazine 31, 96-106.
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
  • Districts of Republican Subordination
L.A. Pautov data
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