Steacyite Mineral Data

General Steacyite Information

Chemical Formula:

K1-x(Ca,Na)2ThSi8O20 (x=0.2 to 0.4)

Composition:

Molecular Weight = 825.70 gm

Potassium 2.84 % K 3.42 % K₂O

Sodium 1.95 % Na 2.63 % Na₂O

Calcium 3.40 % Ca 4.75 % CaO

Thorium 25.29 % Th 28.78 % ThO₂

Manganese 1.33 % Mn 1.72 % MnO

Silicon 27.21 % Si 58.21 % SiO₂

Oxygen 37.98 % O

______ ______

100.00 % 99.52 % = TOTAL OXIDE

Empirical Formula:

K_0.6Na_0.7Ca_0.7Mn²⁺_0.2Th_0.9Si₈O_19.6

Environment:

In cavities in pegmatite veins in nepheline syenite.

IMA Status:

Approved IMA 1982

Locality:

Mont Saint-Hilaire, Quebec, Canada. Link to MinDat.org Location Data.

Name Origin:

Named for Harold R. Steacy, formerly Curator of the National Mineral Collection, Geological Survey of Canada, Ottawa, Canada.

Name Pronunciation:

Steacyite + Pronunciation

Synonym:

Desourdyite

Steacyite Image

Images:

Steacyite

Comments: Square prismatic crystal of steacyite on acicular aegirine.
Location: Mont St. Hilaire, Quebec, Canada. Scale: Not Given.
© Lou Perloff / Photo Atlas of Minerals

Steacyite Crystallography

Axial Ratios:

a:c = 1:1.94854

Cell Dimensions:

a = 7.58, c = 14.77, Z = 2; V = 848.63 Den(Calc)= 3.23

Crystal System:

Tetragonal - Ditetragonal DipyramidalH-M Symbol (4/m 2/m 2/m) Space Group: P 4/mcc

$Help on X Ray Diffraction:$ X Ray Diffraction:

By Intensity(I/I_o): 3.38(1), 5.22(0.9), 7.32(0.9),

Physical Properties of Steacyite

Cleavage:

None

Color:

Brown, Yellow green.

Density:

2.95

Diaphaneity:

Translucent

Fracture:

Brittle - Generally displayed by glasses and most non-metallic minerals.

Habit:

Massive - Uniformly indistinguishable crystals forming large masses.

Habit:

Radial - Crystals radiate from a center without producing stellar forms (e.g. stibnite)

Hardness:

5 - Apatite

Luminescence:

Radioactive.

Luster:

Vitreous - Dull

Streak:

white

Optical Properties of Steacyite

Gladstone-Dale:

CI meas= 0.001 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= 0.087 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1772,KPDmeas= 0.1941,KC= 0.1942
Ncalc = 1.57 - 1.63

Optical Data:

Uniaxial (-), e=1.572, w=1.573, bire=0.0010.

Calculated Properties of Steacyite

Electron Density:

Bulk Density (Electron Density)=2.77 gm/cc
note: Specific Gravity of Steacyite =2.95 gm/cc.

Fermion Index:

Fermion Index = 0.01
Boson Index = 0.99

Photoelectric:

PE_Steacyite= 568.46 barns/electron
U=PE_Steacyite x r_electron=1,575.62 barns/cc.

Radioactivity:

GRapi = 506,988.54 (Gamma Ray American Petroleum Institute Units)
Concentration of Steacyite per GRapi unit =1,972.43 (PPB)

Steacyite is Radioactive as defined in 49 CFR 173.403. Greater than 70 Bq / gram.

Estimated Maximum U.S. Postal Shipping Size (10 mRem/hr limit, Unshielded 10 cm box) 59.99 ± 15.00 grams of pure Steacyite .
Estimated Maximum U.S. Postal Shipping Size (10 mRem/hr limit, Unshielded 100 cm box) 5999.5 ±1499.9 grams of pure Steacyite .

**Estimated Radioactivity from Steacyite** - strong
Specimen Size Weight/Volume (Sphere) *	Calculated Activity Becquerels (Bq)	Calculated Activity Curies (Ci)	Estimated Activity GR(api)	Estimated Exposure (mRem**)/hr If Held in Hand For One Hour
1000 gm / 8.65 cm	11,331,574	3.06E-04	506,988.54	166.68
100 gm / 4.02 cm	1,133,157	3.06E-05	50,698.85	16.67
10 gm / 1.86 cm	113,316	3.06E-06	5,069.89	1.67
1 gm / 8.65 mm	11,332	3.06E-07	506.99	0.17
0.1 gm / 4.02 mm	1,133	3.06E-08	50.70	0.02
0.01 gm / 1.86 mm	113	3.06E-09	5.07	0.00
0.001 gm / 0.87 mm	11	3.06E-10	0.51	0.00

Weight of pure Steacyite in grams (gm) and Calculated Diameter of a Sphere with a Density of 2.95 gm/cc.*
Goverment Estimate of Average Annual Exposure ( 360 mRem) **
Note: 10 microsieverts/hr = 1 mRem/hr **
Max Permissable Adult Dose 50,000 mRem/yr (hands), 15,000 mRem/yr (eyes)
Lethal Dose LD(50) Exposure 400,000 to 500,000 mRem

Steacyite Classification

Dana Class:

63.01.01.01 (63)Cyclosilicate Condensed Rings

(63.01)4-membered rings

(63.01.01)Steacyite Group

63.01.01.01 Steacyite K1-x(Ca,Na)2ThSi8O20(x=0.2to0.4) P 4/mcc 4/m 2/m 2/m

63.01.01.02 Iraqite-(La) K(La,Ce,Th)2(Ca,Na)4(Si,Al)16O40 P 4/mcc 4/m 2/m 2/m

63.01.01.03 Turkestanite! Th(Ca,Na)2(K1-x,[]x)Si8O20•n(H2O) P 4/mcc 4/m 2/m 2/m

63.01.01.04 Arapovite! (U,Th)(Ca,Na)2(K1-x[]x)Si8O20•H2O,x=0.5 P 4/mcc 4/m 2/m 2/m

Strunz Class:

09.CH.10 09 - SILICATES (Germanates)

09.C - Cyclosilicates

09.CH -[Si4O12]8- 4-membered double rings

09.CH.10 Iraqite-(La) K(La,Ce,Th)2(Ca,Na)4(Si,Al)16O40 P 4/mcc 4/m 2/m 2/m

09.CH.10 Steacyite K1-x(Ca,Na)2ThSi8O20(x=0.2to0.4) P 4/mcc 4/m 2/m 2/m

09.CH.10 Turkestanite! Th(Ca,Na)2(K1-x,[]x)Si8O20•n(H2O) P 4/mcc 4/m 2/m 2/m

09.CH.10 Arapovite! (U,Th)(Ca,Na)2(K1-x[]x)Si8O20•H2O,x=0.5 P 4/mcc 4/m 2/m 2/m

Other Steacyite Information

References:

NAME( AntBidBlaNic2) PHYS. PROP.(AntBidBlaNic2) OPTIC PROP.(AntBidBlaNic2)

See Also:

Links to other databases for Steacyite :
1 - Alkali-Nuts(English)
2 - Alkali-Nuts(Francais)
3 - Am. Min. Crystal Structure Database
4 - Athena
5 - EUROmin Project
6 - Ecole des Mines de Paris
7 - GeoScienceWorld
8 - Google Images
9 - Google Scholar
10 - Handbook of Mineralogy (MinSocAm)
11 - Handbook of Mineralogy (UofA)
12 - MinDAT
13 - Mineralienatlas (Deutsch)
14 - Online Mineral Museum
15 - QUT Mineral Atlas
16 - Ruff.Info
17 - Uranium Minerals

Search for Steacyite using:

[AOL] [Bing] [Dog Pile] [GeoScienceWorld] [HotBot] [Ixquick] [Lycos] [MAMMA] [Scirus] [Teoma] [WebCrawler] [Wikipedia] [YAHOO]

Visit our Advertisers for Steacyite :

A Bijoux Google Search for Steacyite
Adam's Minerals Google Search for Steacyite
Cape Minerals Google Search for Steacyite
Dakota Matrix Minerals Google Search for Steacyite
Excalibur Mineral Corp. Google Search for Steacyite
Exceptional Minerals Google Search for Steacyite
John Betts Fine Minerals Search for Steacyite
McDougall Minerals Google Search for Steacyite
Mineral News Website Link
Rock and Mineral Shows Google Search for Steacyite
Weinrich Minerals, Inc. Google Search for Steacyite

Ask about Steacyite here :
Ask-A-Mineralogist from the Mineralogical Society of America
Mindat.org's Discussion Groups
Original Rockhounds Discussion Group
Rockhounds Discussion Group on Yahoo Groups
Mineral Discussion Forum from Fabre Minerals - also available in Español

Print or Cut-and-Paste your Steacyite Specimen Label here :

Steacyite

K1-x(Ca,Na)2ThSi8O20 (x=0.2 to 0.4)
Dana No: 63.01.01.01 Strunz No: 09.CH.10
Locality:

Notes: