Dawsonite Mineral Data

General Dawsonite Information

Chemical Formula:

NaAl(CO3)(OH)2

Composition:

Molecular Weight = 144.00 gm

Sodium 15.97 % Na 21.52 % Na₂O

Aluminum 18.74 % Al 35.40 % Al₂O₃

Hydrogen 1.40 % H 12.51 % H₂O

Carbon 8.34 % C 30.56 % CO₂

Oxygen 55.56 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

NaAl(CO₃)(OH)₂

IMA Status:

Valid Species (Pre-IMA) 1874

Locality:

Feldspathic dike near McGill university, Montreal, Canada. Link to MinDat.org Location Data.

Name Origin:

Named after the Canadian geologist, J. W. Dawson (1820-1899).

Name Pronunciation:

Dawsonite + Pronunciation

Synonym:

ICSD 100140

PDF 42-1346

Dawsonite Image

Images:

Dawsonite

Comments: White, radial crystalline aggregates of dawsonite crystals.
Location: Mont St. Hilaire, Quebec, Canada. Scale: Not Given.
© Lou Perloff / Photo Atlas of Minerals

Dawsonite Crystallography

Axial Ratios:

a:b:c =0.6496:1:0.5381

Cell Dimensions:

a = 6.73, b = 10.36, c = 5.575, Z = 4; V = 388.70 Den(Calc)= 2.46

Crystal System:

Orthorhombic - DipyramidalH-M Symbol (2/m 2/m 2/m) Space Group: Imam

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

By Intensity(I/I_o): 5.7(1), 3.385(0.16), 1.69(0.14),

Forms:

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Forms: ( 0 1 0) ( 0 1 1) ( 1 1 0) ( 1 0 0) ( 0 0 1)

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Crystal Structure:

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Frueh A J , Golightly J P , The Canadian Mineralogist , 9 (1967) p.51-56, The crystal structure of dawsonite NaAl(CO3)(OH)2, Locality: McGill University, Montreal, Quebec, Canada

Physical Properties of Dawsonite

Cleavage:

{110} Perfect

Color:

Colorless, White.

Density:

2.4 - 2.44, Average = 2.42

Diaphaneity:

Transparent

Fracture:

Uneven - Flat surfaces (not cleavage) fractured in an uneven pattern.

Habit:

Acicular - Occurs as needle-like crystals.

Habit:

Encrustations - Forms crust-like aggregates on matrix.

Habit:

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

Hardness:

3 - Calcite

Luminescence:

Non-fluorescent, Short UV=dull white.

Luster:

Vitreous - Silky

Magnetism:

Nonmagnetic

Streak:

white

Optical Properties of Dawsonite

Gladstone-Dale:

CI meas= 0.001 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= 0.017 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2173,KPDmeas= 0.2209,KC= 0.2212
Ncalc = 1.53 - 1.54

Optical Data:

Biaxial (-), a=1.466, b=1.542, g=1.596, bire=0.1300, 2V(Calc)=76, 2V(Meas)=77. Dispersion relatively weak.

Pleochroism (x):

colorless.

Pleochroism (y):

colorless.

Pleochroism (z):

colorless.

Calculated Properties of Dawsonite

Electron Density:

Bulk Density (Electron Density)=2.42 gm/cc
note: Specific Gravity of Dawsonite =2.42 gm/cc.

Fermion Index:

Fermion Index = 0.0011863031
Boson Index = 0.9988136969

Photoelectric:

PE_Dawsonite= 0.94 barns/electron
U=PE_Dawsonite x rElectron Density= 2.27 barns/cc.

Radioactivity:

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

Dawsonite Classification

Dana Class:

16a.03.08.01 (16a)Carbonates - Hydroxyl or Halogen

(16a.03)where (A B)2 (XO3) Zq

(16a.03.08)Dana Group

16a.03.08.01 Dawsonite NaAl(CO3)(OH)2 Imam 2/m 2/m 2/m

Strunz Class:

05.BB.10 05 - CARBONATES (NITRATES)

05.B - Carbonates with additional anions, without H2O

05.BB -With alkalies, etc.

05.BB.10 Dawsonite NaAl(CO3)(OH)2 Imam 2/m 2/m 2/m

Other Dawsonite Information

References:

NAME( Duda&Rejl90) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Ford32)

See Also:

Links to other databases for Dawsonite :
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 - WWW-MINCRYST

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Ask about Dawsonite 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 Dawsonite Specimen Label here :

Dawsonite

NaAl(CO3)(OH)2
Dana No: 16a.03.08.01 Strunz No: 05.BB.10
Locality:

Notes: