Slawsonite Mineral Data

General Slawsonite Information

Chemical Formula:

(Sr,Ca)Al2Si2O8

Composition:

Molecular Weight = 309.65 gm

Strontium 22.64 % Sr 26.77 % SrO

Calcium 1.29 % Ca 1.81 % CaO

Aluminum 15.68 % Al 29.64 % Al₂O₃

Silicon 19.05 % Si 40.75 % SiO₂

Oxygen 41.34 % O

______ ______

100.00 % 98.97 % = TOTAL OXIDE

Empirical Formula:

Sr_0.8Ca_0.1Al_1.8Si_2.1O₈

Environment:

In pectolite veinlets in metamorphosed xenoliths.

IMA Status:

Approved IMA 1977

Locality:

From the Wallowa Mountains, Wallowa County, Oregon, USA. Link to MinDat.org Location Data.

Name Origin:

Named for Chester Baker Slawson (1898-1964, Mineralogist AT THE University of Michigan, Ann Arbor, Michigan, USA.

Name Pronunciation:

Slawsonite + Pronunciation

Synonym:

ICSD 100141

PDF 37-462

Slawsonite Image

Images:

Slawsonite

Comments: White crystalline slawsonite in rock.
Location: Sarisaka, Kagami, Kochi, Japan. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Slawsonite Crystallography

Axial Ratios:

a:b:c =0.9511:1:0.891

Cell Dimensions:

a = 8.888, b = 9.344, c = 8.326, Z = 4; beta = 90.33° V = 691.46 Den(Calc)= 2.97

Crystal System:

Monoclinic - PrismaticH-M Symbol (2/m) Space Group: P 2₁/a

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

By Intensity(I/I_o): 3.708(1), 2.917(0.7), 3.498(0.64),

Crystal Structure:

Mouse
drag1 - LMB Manipulate Structure
drag2 - RMB Resize/Rotate
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S - Stereo Pair on/off
H - Help Screen
I - Data Info
A - Atoms On/Off
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Griffen D T , Ribbe P H , Gibbs G V , American Mineralogist , 62 (1977) p.31-35, The structure of slawsonite, a strontium analog of paracelsian

Physical Properties of Slawsonite

Cleavage:

{001} Good, {010} Fair

Color:

Colorless, Medium gray.

Density:

3.05 - 3.5, Average = 3.27

Diaphaneity:

Semitransparent

Habit:

Aggregates - Made of numerous individual crystals or clusters.

Habit:

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

Habit:

Tabular - Form dimensions are thin in one direction.

Hardness:

5.5-6.5 - Knife Blade-Pyrite

Luminescence:

Fluorescent, Short UV=pinkish red purple.

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Slawsonite

Gladstone-Dale:

CI meas= 0.062 (Fair) - where the CI = (1-KPDmeas/KC)
CI calc= -0.034 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1951,KPDmeas= 0.1769,KC= 0.1887
Ncalc = 1.56 - 1.66

Optical Data:

Biaxial (-), a=1.57-1.573, b=1.581-1.582, g=1.585-1.586, bire=0.0130-0.0150, 2V(Calc)=60-66, 2V(Meas)=55-82. Dispersion r < v medium.

Calculated Properties of Slawsonite

Electron Density:

Bulk Density (Electron Density)=2.86 gm/cc
note: Specific Gravity of Slawsonite =2.97 gm/cc.

Fermion Index:

Fermion Index = 0.02
Boson Index = 0.98

Photoelectric:

PE_Slawsonite= 26.20 barns/electron
U=PE_Slawsonite x rElectron Density= 74.99 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Slawsonite is Not Radioactive

Slawsonite Classification

Dana Class:

76.01.05.02 (76)Tectosilicate Al-Si Framework

(76.01)with Al-Si frameworks

(76.01.05)Paracelsian group

76.01.05.01 Paracelsian BaAl2Si2O8 P 2₁/c 2/m

76.01.05.02 Slawsonite (Sr,Ca)Al2Si2O8 P 2₁/a 2/m

Strunz Class:

09.FA.50 09 - SILICATES (Germanates)

09.F - Tektosilicates without Zeolitic H2O

09.FA -Tektosilicates without additional non-tetrahedral anions, (Al,B):Si = 1:1

09.FA.50 Slawsonite (Sr,Ca)Al2Si2O8 P 2₁/a 2/m

Other Slawsonite Information

References:

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

See Also:

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

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Ask about Slawsonite here :
Ask-A-Mineralogist from the Mineralogical Society of America
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Print or Cut-and-Paste your Slawsonite Specimen Label here :

Slawsonite

(Sr,Ca)Al2Si2O8
Dana No: 76.01.05.02 Strunz No: 09.FA.50
Locality:

Notes: