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Steacyite

A valid IMA mineral species
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About SteacyiteHide

02816440014947046915597.jpg
Harold Robert Steacy
Formula:
K0.3(Na,Ca)2ThSi8O20
Colour:
Gray, dark brown, green, beige
Lustre:
Vitreous, Greasy, Dull
Hardness:
5
Specific Gravity:
2.95
Crystal System:
Tetragonal
Member of:
Name:
Named in 1982 by Guy Perrault and Jan T. Szymaƈski 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.


Unique IdentifiersHide

Mindat ID:
3754
Long-form identifier:
mindat:1:1:3754:5
GUID
(UUID V4):
e30a4d1b-af89-47ed-be55-4dc4d1a94991

IMA Classification of SteacyiteHide

Approved
IMA Formula:
K0.3(Na,Ca)2ThSi8O20
Approval year:
1981

Classification of SteacyiteHide

9.CH.10

9 : SILICATES (Germanates)
C : Cyclosilicates
H : [Si4O12]8- 4-membered double rings
63.1.1.1

63 : CYCLOSILICATES Condensed Rings
1 : Condensed Rings (Steacyite group)
14.16.15

14 : Silicates not Containing Aluminum
16 : Silicates of U

Mineral SymbolsHide

As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.

Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.

SymbolSourceReference
ScyIMA–CNMNCWarr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43
StcThe Canadian Mineralogist (2019)The Canadian Mineralogist (2019) The Canadian Mineralogist list of symbols for rock- and ore-forming minerals (December 30, 2019). download

Physical Properties of SteacyiteHide

Vitreous, Greasy, Dull
Transparency:
Translucent, Opaque
Colour:
Gray, dark brown, green, beige
Hardness:
Cleavage:
None Observed
Density:
2.95 g/cm3 (Measured)    3.32 g/cm3 (Calculated)
Comment:
Measured on porous material.

Optical Data of SteacyiteHide

Type:
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:
Low

Chemistry of SteacyiteHide

Mindat Formula:
K0.3(Na,Ca)2ThSi8O20
Common Impurities:
As,Mn,Pb,F,P

Crystallography of SteacyiteHide

Crystal System:
Tetragonal
Class (H-M):
4/mmm (4/m 2/m 2/m) - Ditetragonal Dipyramidal
Space Group:
P4/mcc
Setting:
P4/mcc
Cell Parameters:
a = 7.58 Å, c = 14.76 Å
Ratio:
a:c = 1 : 1.947
Unit Cell V:
848.06 ų (Calculated from Unit Cell)
Morphology:
Elongated along [001] and showing only the forms {100} and {001}.
Twinning:
Cruciform, by 90° rotation about [010].

Crystal StructureHide

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IDSpeciesReferenceLinkYearLocalityPressure (GPa)Temp (K)
0018511SteacyitePrichard P, Perrault G (1972) Structure cristalline de l'ekanite de St-Hilaire, P.Q. Acta Crystallographica B28 1994-19991972Mont St-Hilaire, Quebec, Canada0293
CIF Raw Data - click here to close

X-Ray Powder DiffractionHide

Powder Diffraction Data:
d-spacingIntensity
3.38 Å(100)
3.32 Å(55)
5.30 Å(45)
2.64 Å(41)
2.00 Å(26)
1.82 Å(20)
2.16 Å(19)

Geological EnvironmentHide

Paragenetic Mode(s):
Paragenetic ModeEarliest Age (Ga)
Stage 4b: Highly evolved igneous rocks>3.0
34 : Complex granite pegmatites
35 : Ultra-alkali and agpaitic igneous rocks

Type Occurrence of SteacyiteHide

General Appearance of Type Material:
Elongated crystals to 2 mm.
Place of Conservation of Type Material:
Ecole Polytechnique, Montreal, Quebec, Canada, number 12480.
Canadian Geological Survey, Ottawa, Ontario, Canada, number 61529.
Canadian Museum of Nature, Ottawa, Canada.
National Museum of Natural History, Washington, D.C., USA, number 149820.
The Natural History Museum, London, England, number 1970,168.
Geological Setting of Type Material:
In pegmatite veins in nepheline syenite.
Associated Minerals at Type Locality:

Synonyms of SteacyiteHide

Other Language Names for SteacyiteHide

Relationship of Steacyite to other SpeciesHide

Member of:
Other Members of this group:
Arapovite(K1-x◻x)(Ca,Na)2U4+Si8O20 (x ~ 0.5)Tet. 4/mmm (4/m 2/m 2/m) : P4/mcc
Iraqite-(La)KCa2(La,Ce,Th)Si8O20Tet. 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:
48 photos of Steacyite associated with Charoite(K,Sr)15-16(Ca,Na)32[Si6O11(O,OH)6]2[Si12O18(O,OH)12]2[Si17O25(O,OH)18]2(OH,F)4 · ~3H2O
47 photos of Steacyite associated with AegirineNaFe3+Si2O6
14 photos of Steacyite associated with QuartzSiO2
12 photos of Steacyite associated with PectoliteNaCa2Si3O8(OH)
11 photos of Steacyite associated with GalenaPbS
4 photos of Steacyite associated with MicroclineK(AlSi3O8)
4 photos of Steacyite associated with FrankameniteK3Na3Ca5(Si12O30)(F,OH)4 · H2O
3 photos of Steacyite associated with Gjerdingenite-NaK2Na(Nb,Ti)4(Si4O12)2(OH,O)4 · 5H2O
3 photos of Steacyite associated with TinaksiteK2Na(Ca,Mn2+)2TiO[Si7O18(OH)]
2 photos of Steacyite associated with Sazhinite

Related Minerals - Strunz-mindat GroupingHide

9.CH.05Hyalotekite(Ba,Pb,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.05ItsiiteBa4Ca2[Si8B4O28]◻Tet. 4 2m : I4 2m
9.CH.05Khvorovite(Pb,Ba,K)4Ca2[Si8B2(Si,B)2O28]FTric.
9.CH.10Iraqite-(La)KCa2(La,Ce,Th)Si8O20Tet. 4/mmm (4/m 2/m 2/m) : P4/mcc
9.CH.10Turkestanite(K,◻)(Ca,Na)2ThSi8O20 · nH2OTet. 4/mmm (4/m 2/m 2/m) : P4/mcc
9.CH.10Arapovite(K1-x◻x)(Ca,Na)2U4+Si8O20 (x ~ 0.5)Tet. 4/mmm (4/m 2/m 2/m) : P4/mcc

Other InformationHide

Notes:
Radioactive. Emits α and ÎČ particles, but not Îł radiation.
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.

Internet Links for SteacyiteHide

References 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 references and 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 (e.g. from pseudomorphs).

All localities listed without proper references should be considered as questionable.
Canada (TL)
 
  • QuĂ©bec
    • MontĂ©rĂ©gie
      • La VallĂ©e-du-Richelieu RCM
        • Mont Saint-Hilaire
Perrault et al. (1982) +2 other references
Germany
 
  • Rhineland-Palatinate
    • Mayen-Koblenz
      • Mendig
        • Mendig
Blass et al. (1994)
Greenland
 
  • Kujalleq
    • Igaliku
      • Narsaarsuk Plateau
Knut Eldjarn ( XRD Geological museum, Oslo)
Guinea
 
  • Conakry Region
Parodi et al. (1987)
a magmatic marker of the evolution of the Central and Equatorial Atlantic. The Canadian Mineralogist (2) +3 other references
Namibia
 
  • Khomas Region
    • Windhoek Rural
      • Aris
Joachim Esche collection (SEM-EDS-analysed) +3 other references
Portugal
 
  • Azores
    • SĂŁo Miguel
Chiappino et al. (2015)
      • Ribeira Grande
Pedro Alves collection and analytical ...
Russia
 
  • Aldan Shield
    • Chara and Tokko Rivers Confluence
Konev et al. (1996)
Kaneva +3 other references
Pavel.M. Kartashov (n.d.) +1 other reference
Kaneva +3 other references
  • Murmansk Oblast
    • Khibiny Massif
Pekov et al. (2004)
USA
 
Minerological Record 18: 361n
 
Mineral and/or Locality  
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