Steacyite (original) (raw)

A valid IMA mineral species

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About SteacyiteHide

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Formula:

K0.3(Na,Ca)2ThSi8O20

Colour:

Gray, dark brown, green, beige

Lustre:

Vitreous, Greasy, Dull

Crystal System:

Tetragonal

Name:

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.

Unique IdentifiersHide

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Long-form identifier:

mindat:1:1:3754:5

e30a4d1b-af89-47ed-be55-4dc4d1a94991

IMA Classification of SteacyiteHide

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IMA Formula:

K0.3(Na,Ca)2ThSi8O20

Classification of SteacyiteHide

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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

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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.

Symbol Source Reference
Scy IMA–CNMNC Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43
Stc The 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

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Transparency:

Translucent, Opaque

Colour:

Gray, dark brown, green, beige

Density:

2.95 g/cm3 (Measured) 3.32 g/cm3 (Calculated)

Comment:

Measured on porous material.

Optical Data of SteacyiteHide

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RI values:

_n_ω = 1.573 _n_ε = 1.572

δ = 0.001

Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.

Chemistry of SteacyiteHide

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Mindat Formula:

K0.3(Na,Ca)2ThSi8O20

Common Impurities:

As,Mn,Pb,F,P

Crystallography of SteacyiteHide

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Crystal System:

Tetragonal

Class (H-M):

4/m m m _(_4/_m_2/_m_2/m ) - Ditetragonal Dipyramidal

Cell Parameters:

a = 7.58 Å, c = 14.76 Å

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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ID Species Reference Link Year Locality Pressure (GPa) Temp (K)
0018511 Steacyite Prichard P, Perrault G (1972) Structure cristalline de l'ekanite de St-Hilaire, P.Q. Acta Crystallographica B28 1994-1999 1972 Mont St-Hilaire, Quebec, Canada 0 293

CIF Raw Data - click here to close

X-Ray Powder DiffractionHide

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Powder Diffraction Data:

d-spacing Intensity
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

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Type Occurrence of SteacyiteHide

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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

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Other Language Names for SteacyiteHide

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Relationship of Steacyite to other SpeciesHide

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Other Members of this group:

Arapovite (K1-x◻x)(Ca,Na)2U4+Si8O20 (x ~ 0.5) Tet. 4/m m m _(_4/_m_2/_m_2/m ) : _P_4/m c c
Iraqite-(La) KCa2(La,Ce,Th)Si8O20 Tet. 4/m m m _(_4/_m_2/_m_2/m ) : _P_4/m c c
Turkestanite (K,◻)(Ca,Na)2ThSi8O20 · nH2O Tet. 4/m m m _(_4/_m_2/_m_2/m ) : _P_4/m c c

Common AssociatesHide

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Associated Minerals Based on Photo Data:

Related Minerals - Strunz-mindat GroupingHide

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9.CH.05 Hyalotekite (Ba,Pb,K)4(Ca,Y)2(B,Be)2(Si,B)2Si8O28(F,Cl) Tric. 1 : _P_1
9.CH.05 Kapitsaite-(Y) (Ba,K,Pb)4(Y,Ca)2Si8(B,Si)4O28F Tric. 1 : _P_1
9.CH.05 Itsiite Ba4Ca2[Si8B4O28]◻ Tet. 42_m_ : I_42_m
9.CH.05 Khvorovite (Pb,Ba,K)4Ca2[Si8B2(Si,B)2O28]F Tric.
9.CH.10 Iraqite-(La) KCa2(La,Ce,Th)Si8O20 Tet. 4/m m m _(_4/_m_2/_m_2/m ) : _P_4/m c c
9.CH.10 Turkestanite (K,◻)(Ca,Na)2ThSi8O20 · nH2O Tet. 4/m m m _(_4/_m_2/_m_2/m ) : _P_4/m c c
9.CH.10 Arapovite (K1-x◻x)(Ca,Na)2U4+Si8O20 (x ~ 0.5) Tet. 4/m m m _(_4/_m_2/_m_2/m ) : _P_4/m c c

Other InformationHide

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Notes:

Radioactive. Emits α and β particles, but not γ 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

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References for SteacyiteHide

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Reference List:

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 (1) 65-75

Localities for SteacyiteHide

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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

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- 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)
Québec Montérégie La Vallée-du-Richelieu RCM Mont Saint-Hilaire ⓘ Poudrette quarry (De-Mix quarry; Demix quarry; Uni-Mix quarry; Carrière Mont Saint-Hilaire; MSH) (TL) Perrault et al. (1982) +2 other references
Germany
Rhineland-Palatinate Mayen-Koblenz Mendig Mendig ⓘ In den Dellen quarries Blaß et al. (1994)
Greenland
Kujalleq Igaliku Narsaarsuk Plateau ⓘ Narssârssuk pegmatite Knut Eldjarn ( XRD Geological museum, Oslo)
Guinea
Conakry Region ⓘ Los Archipelago (Los Islands) Parodi et al. (1987)
ⓘ Rouma Island 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 ⓘ Aris Quarries Joachim Esche collection (SEM-EDS-analysed) +3 other references
Portugal
Azores São Miguel ⓘ Água de Pau Volcano Chiappino et al. (2015)
Ribeira Grande ⓘ Pumice quarry Alves (n.d.)
Russia
Aldan Shield Chara and Tokko Rivers Confluence ⓘ Murunskii Massif Konev et al. (1996)
ⓘ Irkutskii area Kaneva +3 other references
ⓘ Sirenevyi Kamen' Deposit Pavel.M. Kartashov (n.d.) +1 other reference
ⓘ Yakutskiy district Kaneva +3 other references
Murmansk Oblast Khibiny Massif ⓘ Kukisvumchorr Mt Pekov et al. (2004)
USA
ⓘ North Carolina
ⓘ Henderson County Minerological Record 18: 361n