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Steacyite

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Poudrette quarry (Demix quarry; Uni-Mix quarry; Desourdy quarry), Mont Saint-Hilaire, Rouville RCM, Montérégie, Québec, Canada
© JBS 2006

Show Steacyite Photos (40)
Formula:
([ ],K)(Na,Ca)
 
2
(Th,U)[Si
 
8
O
 
20
]
System:TetragonalColour:Gray, dark brown, green, ...
Hardness:5
Name:Named after Harold Robert Steacy (b. 1923), mineralogist and curator, National Mineral Collection, Geological Survey of Canada.
This page provides mineralogical data about Steacyite.

Classification of Steacyite

IMA status:Approved 1981
Strunz 8th edition ID:8/E.10-30
Nickel-Strunz 10th (pending) edition ID:9.CH.10

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

63 : CYCLOSILICATES Condensed Rings
1 : Condensed Rings (Steacyite group)
Hey's CIM Ref.:14.16.15

14 : Silicates not Containing Aluminum
16 : Silicates of U
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Type Occurrence of Steacyite

Type Locality:Poudrette quarry (Demix quarry; Uni-Mix quarry; Desourdy quarry), Mont Saint-Hilaire, Rouville RCM, Montérégie, Québec, Canada
Year of Discovery:1982

Physical Properties of Steacyite

Lustre:Vitreous, Greasy, Dull
Diaphaneity (Transparency):Translucent, Opaque
Colour:Gray, dark brown, green, beige
Hardness (Mohs):5

Crystallography of Steacyite

Crystal System:Tetragonal
Cell Parameters:a = 7.58Å, c = 14.76Å
Ratio:a:c = 1 : 1.947
Unit Cell Volume:V 848.06 ų (Calculated from Unit Cell)

Optical Data of Steacyite

Type:Uniaxial (-)
RI values: nω = 1.573 nε = 1.572
Maximum Birefringence:δ = 0.001

Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Surface Relief:Low

Chemical Properties of Steacyite

Formula:
([ ],K)(Na,Ca)
 
2
(Th,U)[Si
 
8
O
 
20
]
Essential elements:K, Na, O, Si, Th
All elements listed in formula:Ca, K, Na, O, Si, Th, U
Common Impurities:As,Mn,Pb,F,P

Relationship of Steacyite to other Species

Member of Group:
Steacyite Group:
Related Minerals - Nickel-Strunz Grouping):

- +
9.CH.05Hyalotekite
(Ba,Pb,Ca,K)
 
6
(B,Si,Al)
 
2
(Si,Be)
 
10
O
 
28
(F,Cl)
9.CH.05Kapitsaite-(Y)
(Ba,K,Pb)
 
4
(Y,Ca)
 
2
Si
 
8
(B,Si)
 
4
O
 
28
F
9.CH.10Iraqite-(La)
K(Ca,Na)
 
2
(La,Ce,Th)[(Si,Al)
 
8
O
 
20
]
9.CH.10Turkestanite
(K,[ ])(Ca,Na)
 
2
(Th,U)[Si
 
8
O
 
20
] · nH
 
2
O
9.CH.10Arapovite
(K,[ ])(Ca,Na)
 
2
(U,Th)[Si
 
8
O
 
20
] · H
 
2
O
Related Minerals - Hey's Index Grouping:

- +
14.16.1Uranosilite
UO
 
3
 · 7SiO
 
2
14.16.2Coffinite
(U,Th)[(OH)
 
4x
|(SiO
 
4
)
 
1-x
]
14.16.3Soddyite
(UO
 
2
)
 
2
SiO
 
4
·2H
 
2
O
14.16.4Swamboite
UH
 
6
(UO
 
2
)
 
6
(SiO
 
4
)
 
6
·30H
 
2
O
14.16.5Weeksite
K
 
2
(UO
 
2
)
 
2
(Si
 
2
O
 
5
)
 
3
·4H
 
2
O
14.16.6Boltwoodite
(K,Na)(UO
 
2
)[HSiO
 
4
] · 0.5H
 
2
O
14.16.7Natroboltwoodite
(H
 
3
O)(Na,K)UO
 
2
SiO
 
4
·H
 
2
O
14.16.8Cuprosklodowskite
Cu(UO
 
2
)
 
2
[HSiO
 
4
]
 
2
 · 6H
 
2
O
14.16.9Sklodowskite
Mg(UO
 
2
)
 
2
[HSiO
 
4
]
 
2
 · 5H
 
2
O
14.16.10Uranophane
Ca(UO
 
2
)
 
2
[HSiO
 
4
]
 
2
 · 5H
 
2
O
14.16.11β-Uranophane
Ca(UO
 
2
)
 
2
[HSiO
 
4
]
 
2
 · 5H
 
2
O
14.16.12Haiweeite
Ca(UO
 
2
)
 
2
[Si
 
5
O
 
12
(OH)
 
2
]·4.5H
 
2
O
14.16.13Metahaiweeite
Ca(UO
 
2
)
 
2
Si
 
6
O
 
15
·nH
 
2
O
14.16.14Thorogummite
(Th,U)[(OH)
 
4x
|(SiO
 
4
)
 
1-x
]
14.16.16Ekanite
(Ca,Fe
2+
 
,Pb)
 
2
(Th,U)[Si
 
8
O
 
20
]
14.16.17Kasolite
Pb(UO
 
2
)[SiO
 
4
] · H
 
2
O
14.16.18 Orlite
Pb
 
3
(UO
 
2
)
 
3
(Si
 
2
O
 
7
)
 
2
·6H
 
2
O
14.16.19Oursinite
(Co,Mg)(UO
 
2
)
 
2
[HSiO
 
4
]
 
2
 · 6H
 
2
O

Other Names for Steacyite

Synonyms:
IMA1981-EUnnamed (MSH UK-4)
Other Languages:
German:Steacyit
Spanish:Steacyita

Other Information

Health Warning:No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Steacyite

Reference List:Canadian Mineralogist (1982): 20: 59-63.

American Mineralogist (1983): 68: 472.

Acta Crystallographica: B28: 1994-1999.

European Journal of Mineralogy (1993): 5: 971.

Internet Links for Steacyite

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  • Raman and XRD data at RRUFF project
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    Localities for Steacyite

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