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About DalyiteHide

Reginald Aldworth Daly
Colourless, brown
Crystal System:
Member of:
Named by Rene von Tassel in 1952 for Reginald Aldworth Daly (March 18, 1871 Nepanee, Ontario, Canada – September 19, 1957 Cambridge, Massachusetts, USA). Daly was professor at Harvard University and was one of the most brilliant igneous petrologists and established many geological principles. There are Daly Craters on both the Moon and Mars named in his honor.
Dalyite from Terceira ignimbrites contains some Na and minor Hf and Ti, but does not readily incorporate Fe, Mg and Ba.

Classification of DalyiteHide

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

9 : SILICATES (Germanates)
E : Phyllosilicates
A : Single nets of tetrahedra with 4-, 5-, (6-), and 8-membered rings

72 : PHYLLOSILICATES Two-Dimensional Infinite Sheets with Other Than Six-Membered Rings
2 : Two-Dimensional Infinite Sheets with Other Than Six-Membered Rings with 4-, 6-, and 8-membered rings

14 : Silicates not Containing Aluminum
10 : Silicates of Zr or Hf

Physical Properties of DalyiteHide

Transparent, Translucent
Colourless, brown
7½ on Mohs scale

Optical Data of DalyiteHide

Biaxial (-)
RI values:
nα = 1.575 nβ = 1.590 nγ = 1.601
Measured: 72° , Calculated: 80°
Max Birefringence:
δ = 0.026
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
very weak

Chemical Properties of DalyiteHide

Common Impurities:

Chemical AnalysisHide

Oxide wt%:
SiO263.07 %61.85 %
Al2O30.06 % %
TiO21.23 % %
ZrO219.37 %21.70 %
CaO0.02 % %
MgO0.10 % %
MnO0.02 % %
FeO0.28 % %
K2O15.60 %14.60 %
Na2O0.04 %1.75 %
BaO0.11 % %
P2O50.04 % %
Fe2O3 %0.37 %
H2O %0.64 %
Total:99.94 %100.91 %
Sample references:
1Dalsfjorden, Askvoll, Sogn og Fjordane, NorwayRobins, B., Furnes, H., Ryan P. (1983): A New Occurrence of Dalyite. Mineralogical Magazine, 47, 93-94.
2Type SpecimenGreen Mountain, Ascension Island, Saint HelenaVan Tassel, R. (1952) Dalyite, a new potassium zirconium silicate, from Ascension Island, Atlantic. Mineralogical Magazine. 29: 850-857

Crystallography of DalyiteHide

Crystal System:
Cell Parameters:
a = 7.51 Å, b = 7.73 Å, c = 7 Å
α = 106°, β = 113.5°, γ = 99.5°
a:b:c = 0.972 : 1 : 0.906
Unit Cell V:
340.35 ų (Calculated from Unit Cell)

Occurrences of DalyiteHide

Paragenetic Mode(s):
•  Granitic

Type Occurrence of DalyiteHide

Geological Setting of Type Material:
Ejected blocks of alkalic granite in trachytic and basaltic tuffs.
Van Tassel, R. (1952): Dalyite, a new potassium zirconium silicate from Ascension Island, Atlantic. Mineralogical Magazine, 29, 850-857

Other Language Names for DalyiteHide


Relationship of Dalyite to other SpeciesHide

Member of:
Other Members of this group:
Sazhinite-(La)Na3La[Si6O15] · 2H2OOrth. mm2 : Pmm2

Common AssociatesHide

Associated Minerals Based on Photo Data:
Chevkinite-(Ce)3 photos of Dalyite associated with Chevkinite-(Ce) on mindat.org.
Aegirine1 photo of Dalyite associated with Aegirine on mindat.org.
Quartz1 photo of Dalyite associated with Quartz on mindat.org.
Feldspar Group1 photo of Dalyite associated with Feldspar Group on mindat.org.
Janhaugite1 photo of Dalyite associated with Janhaugite on mindat.org.
Britholite Group1 photo of Dalyite associated with Britholite Group on mindat.org.

Related Minerals - Nickel-Strunz GroupingHide

9.EA.05CuprorivaiteCaCuSi4O10Tet. 4/mmm (4/m 2/m 2/m) : P4/ncc
9.EA.05EffenbergeriteBaCuSi4O10Tet. 4/mmm (4/m 2/m 2/m) : P4/ncc
9.EA.10EkaniteCa2ThSi8O20Tet. 4 2 2 : I4 2 2
9.EA.15Fluorapophyllite-(K)KCa4(Si8O20)(F,OH) · 8H2OTet. 4/mmm (4/m 2/m 2/m) : P4/mnc
9.EA.15Hydroxyapophyllite-(K)KCa4(Si8O20)(OH,F) · 8H2OTet.
9.EA.15Fluorapophyllite-(Na)NaCa4(Si8O20)F · 8H2OOrth.
9.EA.20MagadiiteNa2Si14O29 · 11H2OMon.
9.EA.30Sazhinite-(La)Na3La[Si6O15] · 2H2OOrth. mm2 : Pmm2
9.EA.35ArmstrongiteCaZr[Si6O15] · 3H2OMon.
9.EA.40OkeniteCa10Si18O46 · 18H2OTric. 1 : P1
9.EA.45NekoiteCa3Si6O15·7H2OTric. 1 : P1
9.EA.50CavansiteCa(VO)Si4O10 · 4H2OOrth. mmm (2/m 2/m 2/m)
9.EA.55PentagoniteCa(VO)Si4O10 · 4H2OOrth. mm2
9.EA.60PenkvilksiteNa4Ti2Si8O22 · 4H2OOrth. mmm (2/m 2/m 2/m) : Pbcn
9.EA.60TumchaiteNa2Zr(Si4O11) · 2H2OMon.
9.EA.65NabesiteNa2BeSi4O10 · 4H2OOrth. 2 2 2 : P21 21 21
9.EA.70Ajoite(K,Na)Cu7AlSi9O24(OH)6 · 3H2OTric.
9.EA.75ZeravshaniteNa2Cs4Zr3[Si18O45]*2H2OMon. 2/m : B2/b
9.EA.80Bussyite-(Ce)(Ce,REE)3(Na,H2O)6MnSi9Be5(O,OH)30F4Mon. 2/m : B2/b
9.EA.85PlumbophyllitePb2Si4O10 · H2OOrth. mmm (2/m 2/m 2/m) : Pbcn

Related Minerals - Dana Grouping (8th Ed.)Hide•6H2O

Related Minerals - Hey's Chemical Index of Minerals GroupingHide

14.10.1ZirconZr(SiO4)Tet. 4/mmm (4/m 2/m 2/m) : I41/amd
14.10.2HafnonHfSiO4Tet. 4/mmm (4/m 2/m 2/m) : I41/amd
14.10.5VlasoviteNa2ZrSi4O11Mon. 2/m : B2/b
14.10.6Keldyshite(Na,H)2ZrSi2O7Tric. 1 : P1
14.10.7GaidonnayiteNa2Zr(Si3O9) · 2H2OOrth. mmm (2/m 2/m 2/m) : Pmna
14.10.8TerskiteNa4ZrSi6O16 · 2H2OOrth.
14.10.9ElpiditeNa2ZrSi6O15 · 3H2OOrth.
14.10.10HilairiteNa2Zr[SiO3]3 · 3H2OTrig.
14.10.11PetarasiteNa5Zr2(Si6O18)(Cl,OH) · 2H2OMon. 2/m : P21/m
14.10.15KostyleviteK2Zr(Si3O9) · H2OMon.
14.10.16UmbiteK2(Zr,Ti)Si3O9 · H2OOrth.
14.10.17ParaumbiteK3Zr2H(Si3O9)2 · nH2OOrth.
14.10.18GeorgechaoiteNaKZr[Si3O9] · 2H2OOrth. mm2
14.10.20CalciocatapleiiteCaZr(Si3O9) · 2H2O
14.10.21CalciohilairiteCaZr[SiO3]3 · 3H2OTrig.
14.10.22ArmstrongiteCaZr[Si6O15] · 3H2OMon.
14.10.23Lemoynite(Na,K)2CaZr2Si10O26 · 5H2OMon. 2/m : B2/b
14.10.24CatapleiiteNa2Zr(Si3O9) · 2H2OMon.
14.10.26LovozeriteNa2Ca(Zr,Ti)(Si6O12)[(OH)4O2] · H2OMon.
14.10.27Låvenite(Na,Ca)2(Mn2+,Fe2+)(Zr,Ti)(Si2O7)(O,OH,F)2Mon. 2/m : P21/b
14.10.28PenkvilksiteNa4Ti2Si8O22 · 4H2OOrth. mmm (2/m 2/m 2/m) : Pbcn
14.10.29DarapiositeK(Na,◻,K)2(Li,Zn,Fe)3(Mn,Zr,Y)2[Si12O30]Hex. 6/mmm (6/m 2/m 2/m) : P6/mcc
14.10.31KomkoviteBaZr[Si3O9] · 3H2OTrig.

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 DalyiteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Van Tassel R, Hey. M. H. (1952) Dalyite, a new potassium zirconium silicate, from Ascension Island, Atlantic. Mineralogical Magazine 29: 850-857
American Mineralogist: 37: 1071.
Robins,B., Furnes, H. and P. Ryan (1983): A New Occurrence of Dalyite. Mineralogical Magazine. 47: 93-94
Zeitschrift für Kristallographie, Kristallgeometrie, Kristallphysik, Kristallchemie: 121: 349-368.
Jeffery, A.J., Gertisser, R., Jackson, R.A., O'Driscoll, B., Kronz, A. (2016): On the compositional variability of dalyite, K2ZrSi6O15: a new occurrence from Terceira, Azores. Mineralogical Magazine, 80, 547-565.

Internet Links for DalyiteHide

Localities for DalyiteHide

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.
  • Eastern Antarctica
    • Queen Maud Land
Handbook of Mineralogy - Anthony, Bideaux, Bladh, Nichols; Harris, C., & Rickard, R. S. (1987). Rare-earth-rich eudialyte and dalyite from a peralkaline granite dyke at Straumsvola, Dronning Maud Land, Antarctica. Canadian Mineralogist, 25, 755-762.
  • Québec & Newfoundland and Labrador
Miller (1996), Canadian Mineralogist: 34:349-371; Salvi & Williams-Jones (1995); Am.Min.: 80:1031-1040; Miller (1990), Newfoundland Dept. of Mines & Energy Geol. Sur. Report 90-1: 171-182.; A. Kerr and H. Rafuse (2012) Rare-earth element (REE) geochemistry of the Strange Lake deposits: Implications for resource estimation and metallogenic models. Newfoundland and Labrador Department of Natural Resources Current Research 2012 pp39-60; BIRKETT, T.C., MILLER, R.R., ROBERTS, A.C., & MARIANO, A.N. (1992) Zirconium bearing minerals from the Strange Lake intrusive complex, Quebec Labrador. Canadian Mineralogist, 30, 191-205.
  • Erongo Region
    • Dâures
      • Brandberg Area
        • Brandberg Complex
Economic Geology, Vol. 97, 2002, pp. 399–413
  • Oppland
    • Lunner
      • Nordmarka
Raade, G. & Mladeck, M. H. (1983): Janhaugite Na3Mn3Ti2SiO4O15(OH,F,O)3, a new mineral from Norway. American Mineralogist, 68, 1216-1219; Raade, G. (2005): Gjerdingen-ekeritten, en unik mineralforekomst. Norsk Bergverksmuseum Skrift nr. 30, 2005, p 17.
  • Sogn og Fjordane
    • Askvoll
Furnes, H., Mitchell, J.G., Robins, B., Ryan, P., Skjerlie, F. J. (1982): Petrography and geochemistry of peralkaline, ultrapotassic syenite dykes of Middle Permian age, Sunnfjord, West Norway. Norsk Geologisk Tidsskrift, 62, 147-159; Robins, B., Furnes, H., Ryan P. (1983): A New Occurrence of Dalyite. Mineralogical Magazine, 47, 93-94.
  • Azores District
    • São Miguel Island
      • Água de Pau Massif
Cann, J.R. (1967): A second occurrence of dalyite and the petrology of some ejected syenite blocks from Sao Miguel, Azores. Mineralogical Magazine, 36, 227-232; Widom, E., Gill, J. B., Schmincke, H. -U. (1993): Syenite nodules as a long-term record of magmatic activity in Agua de Pau volcano, São Miguel, Azores. Journal of Petrology, 34, 929-953; Ridolfi, F., Renzulli, A., Santi, P., Upton, B. G. J. (2003): Evolutionary stages of crystallisation of weakly peralkaline syenites: evidence from ejecta in the plinian deposits of Agua de Pau volcano (São Miguel, Azores Islands). Mineralogical Magazine, 67, 749-767.
    • Terceira Island
      • Angra do Heroísmo
Jeffery, A.J., Gertisser, R., Jackson, R.A., O'Driscoll, B., Kronz, A. (2016): On the compositional variability of dalyite, K2ZrSi6O15: a new occurrence from Terceira, Azores. Mineralogical Magazine, 80, 547-565.
  • Eastern-Siberian Region
    • Sakha Republic (Yakutia)
      • Aldan Shield
        • Chara and Tokko Rivers Confluence
[Lapis 1993:4 p.13-20]
Saint Helena
  • Ascension Island
C. Harris, G. Cressey, J. D. Bell, F. B. Atkins and S. Beswetherick (1982) An Occurrence of Rare-Earth-Rich Eudialyte from Ascension Island, South Atlantic. Mineralogical Magazine 46:421-425.
Van Tassel, R. [ with a microchemical analysis by Hey, M.H.] (1952): Dalyite, a new potassium zirconium silicate from Ascension Island, Atlantic. Mineralogical Magazine, 29, 850-857. Fleet, S.G. (1965): The crystal structure of dalyite. Zeitschrift für Krystallographie, 121, 349-368.
Van Tassel, R. [ with a microchemical analysis by Hey, M.H.] (1952): Dalyite, a new potassium zirconium silicate from Ascension Island, Atlantic. Mineralogical Magazine, 29, 850-857.
  • Castile-La Mancha
    • Albacete
      • Hellín
        • Cancarix
E. Salvioli-mariani et al. , Eur. J. Mineral. , 1996, 8, pp. 1027-1039.; Mineralogical Magazine 1988 52 : 705-708
  • Montana
    • Meagher Co.
www.cseg.ca/conferences/2000/376.PDF; Chakhmouradian A.R., Mitchell R.H. (2002): The mineralogy of Ba- and Zr-rich alkaline pegmatites from Gordon Butte, Crazy Mountains (Montana, USA): comparisons between potassic and sodic agpaitic pegmatites. Contrib. Mineral. Petrol., 143, 93-114.
Mineral and/or Locality  
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