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Neil Armstrong
CaZr[Si6O15] · 3H2O
Dark to light brown
Specific Gravity:
2.562 - 2.593
Crystal System:
Named after Neil Armstrong (August 5 1930 Wapakoneta, Ohio - August 25 2012 Cincinnati Ohio), American astronaut, who landed on the moon.
This page provides mineralogical data about Armstrongite.

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Classification of ArmstrongiteHide


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
5 : Two-Dimensional Infinite Sheets with Other Than Six-Membered Rings with corrugated and complex layers

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

Physical Properties of ArmstrongiteHide

Dark to light brown
Brownish white
4½ on Mohs scale
VHN100=310 - 330 - Vickers
Very brittle
Very Good
Perfect on {001}
Good on {100}
2.562 - 2.593 g/cm3 (Measured)    2.71 g/cm3 (Calculated)

Optical Data of ArmstrongiteHide

Biaxial (-)
RI values:
nα = 1.563 nβ = 1.569 nγ = 1.573
Max Birefringence:
δ = 0.010
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
strong r < v

Chemical Properties of ArmstrongiteHide

CaZr[Si6O15] · 3H2O
IMA Formula:
CaZrSi6O15 · 2H2O
Common Impurities:

Crystallography of ArmstrongiteHide

Crystal System:
Cell Parameters:
a = 14.04 Å, b = 14.16 Å, c = 7.81 Å
β = 109.55°
a:b:c = 0.992 : 1 : 0.552
Unit Cell V:
1,463.17 ų (Calculated from Unit Cell)
Crystals to 2cm, aggregates
Polysynthetic, by rotation on [100]

Type Occurrence of ArmstrongiteHide

Synonyms of ArmstrongiteHide

Other Language Names for ArmstrongiteHide

Common AssociatesHide

Associated Minerals Based on Photo Data:
Aegirine8 photos of Armstrongite associated with Aegirine on
Quartz4 photos of Armstrongite associated with Quartz on
Orthoclase3 photos of Armstrongite associated with Orthoclase on
Gittinsite2 photos of Armstrongite associated with Gittinsite on

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.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 · 3H2OOrth.

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.
14.10.23Lemoynite(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 ArmstrongiteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Vladykin, N.V., Kovalenko, V.I., Kashaev, A.A., Sapozhnikov, A.N., Pisarskaya, V.A. (1973) A new silicate of calcium and zirconium – armstrongite. Doklady Akademii Nauk SSSR: 209: 1185-1188.
Fleischer, M. (1974) New mineral names. American Mineralogist: 59: 208-212.
Soviet Physics – Crystallography: 23: 593.
Kabalov, Y.K., Zubkova, N.V., Pushcharovsky, D.Y., Schneider, J., Sapozhnikov, A.N. (2000) Powder Rietveld refinement of armstrongite, CaZr[Si6O15]·3H2O. Zeitschrift für Kristallographie: 215: 757-761.
Jambor, J.L., Roberts, A.C. (2001) New mineral names. American Mineralogist: 86: 1534-1537.
Mesto, E., Kaneva, E., Schingaro, E., Vladykin, N., Lacalamita, M., Scordari, F. (2014) Armstrongite from Khan Bogdo (Mongolia): Crystal structure determination and implications for zeolite-like cation exchange properties. American Mineralogist: 99: 2424-2432.

Internet Links for ArmstrongiteHide

Localities for ArmstrongiteHide

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.
  • New South Wales
    • Lincoln Co.
      • Dubbo district
  • Newfoundland and Labrador
Handbook of Mineralogy
  • Québec & Newfoundland and Labrador
Powder Diffraction Jour. v.2 no.1, March1987; Canadian Mineralogist Vol. 34, pp.349-371 (1996); 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.
  • Gobi Desert
Kynicky, J., Chakhmouradian, A.R., Xu, C., Krmicek & Galilova, M. (2011): Distribution aand evolution of zirconium mineralization in peralkaline granites and associated pegmatites of the Khan Bogd Complex, southern Mongolia. Canadian Mineralogist. 49, 947-965.; J Kynický, C Xu, J Mašek, O Jaroš, H Káňová (2009) Arfvedsonite pegmatites of Khan Bogd massif, Mongolia: Zr mineralization. pp222-224 in Czech
Vladykin N.V., Kovalenko V.I., Dorfman M.D. (1981) Mineralogical and geochemical pecularities of Khan Bogdo massif of an alkaline granites (MPR), - Moscow, Nauka, p. 136 (in Rus.).
  • Hovd Aimag (Khovd Aimag)
    • Altai Mts
      • Khaldzan Buragtag massif
U. Kempe, J. Götze, S. Dandar and D. Habermann (1999) Magmatic and Metasomatic Processes During Formation of the Nb-Zr-REE Deposits Khaldzan Buregte and Tsakhir (Mongolian Altai): Indications from a Combined CL-SEM Study. Mineralogical Magazine 63:165-177.
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