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About SteacyiteHide

Harold Robert Steacy
Gray, dark brown, green, beige
Vitreous, Greasy, Dull
Crystal System:
Member of:
Named in 1982 by Guy Perrault and Jan T. Szymaňski in honor of Harold Robert Steacy [June 7, 1923 Ottawa, Ontario, Canada - April 7, 2012 Ottawa, Ontario, Canada], mineralogist, former Curator of the National Mineral Collection, Geological Survey of Canada, for his contributions to Canadian mineralogy.
This page provides mineralogical data about Steacyite.

Classification of SteacyiteHide

Approval Year:

9 : SILICATES (Germanates)
C : Cyclosilicates
H : [Si4O12]8- 4-membered double rings

63 : CYCLOSILICATES Condensed Rings
1 : Condensed Rings (Steacyite group)

14 : Silicates not Containing Aluminum
16 : Silicates of U

Physical Properties of SteacyiteHide

Vitreous, Greasy, Dull
Translucent, Opaque
Gray, dark brown, green, beige

Optical Data of SteacyiteHide

Uniaxial (-)
RI values:
nω = 1.573 nε = 1.572
Max Birefringence:
δ = 0.001
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:

Chemical Properties of SteacyiteHide

IMA Formula:
Common Impurities:

Crystallography of SteacyiteHide

Crystal System:
Class (H-M):
4/mmm (4/m 2/m 2/m) - Ditetragonal Dipyramidal
Space Group:
Cell Parameters:
a = 7.58 Å, c = 14.76 Å
a:c = 1 : 1.947
Unit Cell V:
848.06 ų (Calculated from Unit Cell)

Type Occurrence of SteacyiteHide

Synonyms of SteacyiteHide

Other Language Names for SteacyiteHide

Simplified Chinese:斯硅钾钍钙石
Traditional Chinese:斯矽鉀釷鈣石

Relationship of Steacyite to other SpeciesHide

Member of:
Other Members of this group:
Arapovite(K1-xx)(Ca,Na)2U4+Si8O20 (x ~ 0.5)Tet. 4/mmm (4/m 2/m 2/m) : P4/mcc
Turkestanite(K,◻)(Ca,Na)2ThSi8O20 · nH2OTet. 4/mmm (4/m 2/m 2/m) : P4/mcc

Common AssociatesHide

Associated Minerals Based on Photo Data:
Charoite28 photos of Steacyite associated with Charoite on mindat.org.
Aegirine22 photos of Steacyite associated with Aegirine on mindat.org.
Quartz14 photos of Steacyite associated with Quartz on mindat.org.
Galena11 photos of Steacyite associated with Galena on mindat.org.
Pectolite5 photos of Steacyite associated with Pectolite on mindat.org.
Microcline4 photos of Steacyite associated with Microcline on mindat.org.
Frankamenite4 photos of Steacyite associated with Frankamenite on mindat.org.
Tinaksite3 photos of Steacyite associated with Tinaksite on mindat.org.
Gjerdingenite-Na3 photos of Steacyite associated with Gjerdingenite-Na on mindat.org.
Fluorapophyllite-(K)2 photos of Steacyite associated with Fluorapophyllite-(K) on mindat.org.

Related Minerals - Nickel-Strunz GroupingHide

9.CH.05Hyalotekite(Pb,Ba,K)4(Ca,Y)2(B,Be)2(Si,B)2Si8O28(F,Cl)Tric. 1 : P1
9.CH.05Kapitsaite-(Y)(Ba,K,Pb)4(Y,Ca)2Si8(B,Si)4O28FTric. 1 : P1
9.CH.10Turkestanite(K,◻)(Ca,Na)2ThSi8O20 · nH2OTet. 4/mmm (4/m 2/m 2/m) : P4/mcc
9.CH.10Arapovite(K1-xx)(Ca,Na)2U4+Si8O20 (x ~ 0.5)Tet. 4/mmm (4/m 2/m 2/m) : P4/mcc

Related Minerals - Dana Grouping (8th Ed.)Hide,Ce,Th)Si8O20Tet.

Related Minerals - Hey's Chemical Index of Minerals GroupingHide

14.16.1UranosiliteUO3 · 7SiO2Orth.
14.16.2CoffiniteU(SiO4) · nH2OTet.
14.16.3Soddyite(UO2)2SiO4 · 2H2OOrth.
14.16.5WeeksiteK2(UO2)2(Si5O13) · 4H2OOrth.
14.16.6Boltwoodite(K,Na)(UO2)(SiO3OH) · 1.5H2OMon. 2 : P21
14.16.7NatroboltwooditeNa(UO2)(SiO3OH) · H2O
14.16.8CuprosklodowskiteCu(UO2)2(SiO3OH]2 · 6H2OTric. 1 : P1
14.16.9SklodowskiteMg(UO2)2(SiO3OH)2 · 6H2OMon. 2/m : B2/m
14.16.10UranophaneCa(UO2)2(SiO3OH)2 · 5H2OMon. 2 : P21
14.16.11Uranophane-βCa(UO2)2(SiO3OH)2 · 5H2OMon. 2/m : P21/b
14.16.12HaiweeiteCa(UO2)2[Si5O12(OH)2] · 6H2OOrth. mmm (2/m 2/m 2/m) : Pbcn
14.16.13MetahaiweeiteCa(UO2)2Si6O15 · nH2O
14.16.16EkaniteCa2ThSi8O20Tet. 4 2 2 : I4 2 2
14.16.17KasolitePb(UO2)[SiO4] · H2OMon. 2/m : P21/b
14.16.18OrlitePb3(UO2)3(Si2O7)2 · 6H2O
14.16.19OursiniteCo(UO2)2(SiO3OH)2 · 6H2OOrth. mmm (2/m 2/m 2/m) : Cmca

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.

Steacyite in petrologyHide

An essential component of rock names highlighted in red, an accessory component in rock names highlighted in green.

References for SteacyiteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Chromy, B. (1973) The wee crystals. Earth Science, 1973, 227-278. [see http://www.mindat.org/mesg-6-367561.html]
Perrault, G., Szymański, J.T. (1982) Steacyite, a new name, and a re-evaluation of the nomenclature of "ekanite"–group minerals. The Canadian Mineralogist, 20, 59-63.
Szymański, J.T., Owens, D.R., Roberts, A.C., Ansell, H,G., Chao, G.Y. (1982) A mineralogical study and crystal-structure determination of nonmetamict ekanite, ThCa₂Si8O20. The Canadian Mineralogist, 20, 65-75.

Internet Links for SteacyiteHide

Localities for SteacyiteHide

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.
Canada (TL)
  • Québec
    • Montérégie
      • La Vallée-du-Richelieu RCM
        • Mont Saint-Hilaire
PERRAULT, G., and SZYMAŃSKI, J.T. (1982)Steacyite, a new name and a re- evaluation of the nomenclature of "ekanite" group minerals. Canadian Mineralogist, 20, 59-63. Horváth, L and Gault, R.A. (1990), The mineralogy of Mont Saint-Hilaire Quebec. Mineralogical Record: 21: 284-359.
  • Greenland
    • Kujalleq
      • Narsaq
        • Igaliku (Igaliko)
          • Narsaarsuk Plateau
Knut Eldjarn ( XRD Geological museum, Oslo)+ chemical (ICP)
  • Rhineland-Palatinate
    • Mayen-Koblenz
      • Mendig
        • Niedermendig
Blass, G.; Graf, H.W., Neufunde von bekannten Fundorten (IX), Mineralien-Welt 5/1,18, 1994
Parodi, G. C., & Della Ventura, G. (1987). Steacyite from the Rouma Isle (Los Islands, Republic of Guinea). Neues Jarbuch fur Mineralogie, Mh., Jg. 1987, H. 5, 233-239
Parodi, G. C., & Della Ventura, G. (1987). Steacyite from the Rouma Isle (Los Islands, Republic of Guinea). Neues Jarbuch fur Mineralogie, Mh., Jg. 1987, H. 5, 233-239. ; Moreau, C., Ohnenstetter, D., Demaiffe, D., & Robineau, B. (1996). The Los Archipelago nepheline syenite ring-structure; a magmatic marker of the evolution of the Central and Equatorial Atlantic. The Canadian Mineralogist, 34(2), 281-299.; Biagioni, C., Bonaccorsi, E., Merlino, S., Parodi, G. C., Perchiazzi, N., Chevrier, V., & Bersani, D. (2010). Roumaite,(Ca, Na,□) 3 (Ca, REE, Na) 4 (Nb, Ti)[Si2O7] 2 (OH) F3, from Rouma Island, Los Archipelago, Guinea: a new mineral species related to dovyrenite. The Canadian Mineralogist, 48(1), 17-28.
  • Khomas Region
    • Windhoek District
      • Aris
Joachim Esche collection (SEM-EDS-analysed); Horváth collection XRD & EDS analyzed; Blaß, G., Kolitsch, U., Tremmel, G., Esche, J. (2016): Neue Mineralienfunde aus den Phonolithbrüchen von Aris in Namibia. Mineralien-Welt 27 (4), 48-60 (in German); Kolitsch, U., Blaß, G., Jahn, S., Cámara, F., von Bezing, L., Wartha, R. R., Tremmel, G., Sturla, M., Cerea, P., Skebo, M. and Ciriotti, M. E. (2016): Aris - mineralogy of the famous alkaline phonolite. AMI - Associazione Micromineralogica Italiana, Cremona, Italy, 95 pp.
  • Azores
    • São Miguel Island
      • Água de Pau Massif
Chiappino, L., Astolfi, M., Bracco, R., Marchesini, M. & Selmi, P. (2015): I minerali del Vulcano di Fogo (Agua de Pau), São Miguel, Azzorre, Portogallo. Rivista Mineralogica Italiana 39(4), 220-250 (in Italian). Samples collected by Luigi Chiappino and analysed by Dr. Anthony Kampf, Natural History Museum of Los Angeles County, USA
Pedro Alves collection and analytical data
  • Murmansk Oblast
    • Khibiny Massif
Pekov, I.V. & Podlesnyi, A.S. (2004): Kukisvumchorr Deposit: Mineralogy of Alkaline Pegmatites and Hydrotermalites. Mineralogical Almanac, vol. 7, 140 pages + xxiv photo's pages
  • Sakha Republic (Yakutia)
    • Aldan Shield
      • Chara and Tokko Rivers Confluence
Konev, A.A., Vorob'yev, E.I., and Lazebnik, K.A. (1996) The Mineralogy of the Murun Massif. Russian Academy of Science Press, Siberian Branch, Novosbirsk, Russia (in Rus.)
Pavel M. Kartashov data; Solyanik, V. A., Pakhomova, V. A., & Ushkova, M. A. (2008). Charoite–a champion among mineralogical discoveries in the second half of the 20th century. The Journal of the Gemmological Association of Hong Kong, 29, 77-80.
Minerological Record 18: 361n
Mineral and/or Locality  
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