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Lawsonite Mineral Data

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General Lawsonite Information

Help on Chemical  Formula: Chemical Formula: CaAl2Si2O7(OH)2•(H2O)
Help on Composition: Composition: Molecular Weight = 314.24 gm
   Calcium   12.75 %  Ca   17.85 % CaO
   Aluminum  17.17 %  Al   32.45 % Al2O3
   Silicon   17.88 %  Si   38.24 % SiO2
   Hydrogen   1.28 %  H    11.47 % H2O
   Oxygen    50.91 %  O
            ______        ______ 
            100.00 %      100.00 % = TOTAL OXIDE
Help on Empirical Formula: Empirical Formula: CaAl2Si2O7(OH)2•(H2O)
Help on Environment: Environment: Originally described from a crystalline schist associated with serpentine. Also found as a secondary mineral in altered gabbros and diorites.
Help on IMA Status: IMA Status: Valid Species (Pre-IMA) 1895
Help on Locality: Locality: Reed Station, Tiburon peninsula, Marin County, California, USA. Link to MinDat.org Location Data.
Help on Name Origin: Name Origin: Named for Andrew Cowper Lawson (1861-1952), Scottish-American geologist.
Help on Name Pronunciation: Name Pronunciation: Lawsonite + Pronunciation Say LAWSONITE
Help on Synonym: Synonym: ICSD 80835
  PDF 13-533

Lawsonite Image

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Comments: Glaucophane schist with a heavy druse of lawsonite crystals.
Location: Reed Station, Tiburon, Marin County, California, USA. Scale: Crystal size 7 mm.
© John Veevaert

Lawsonite Crystallography

Help on Axial Ratios: Axial Ratios: a:b:c =1.5051:1:2.2488
Help on Cell Dimensions: Cell Dimensions: a = 8.79, b = 5.84, c = 13.133, Z = 4; V = 674.16 Den(Calc)= 3.10
Help on Crystal System: Crystal System: Orthorhombic - Dipyramidal H-M Symbol (2/m 2/m 2/m) Space Group: Ccmm
Help on X Ray Diffraction: X Ray Diffraction: By Intensity(I/Io): 2.624(1), 1.55(0.8), 2.726(0.7),

Physical Properties of Lawsonite

Help on Cleavage: Cleavage: {010} Perfect, {001} Perfect, {110} Poor
Help on Color: Color: Colorless, White, Gray, Blue, Pinkish.
Help on Density: Density: 3.09
Help on Diaphaneity: Diaphaneity: Translucent to transparent
Help on Fracture: Fracture: Brittle - Uneven - Very brittle fracture producing uneven fragments.
Help on Habit: Habit: Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline).
Help on Habit: Habit: Tabular - Form dimensions are thin in one direction.
Help on Hardness: Hardness: 7.5 - Garnet
Help on Luminescence: Luminescence: Non-fluorescent.
Help on Luster: Luster: Vitreous - Greasy
Help on Magnetism: Magnetism: Nonmagnetic
Help on Streak: Streak: white

Optical Properties of Lawsonite

Help on Gladstone-Dale: Gladstone-Dale: CI meas= 0.022 (Excellent) - where the CI = (1-KPDmeas/KC)
CI calc= 0.025 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2176,KPDmeas= 0.2183,KC= 0.2232
Ncalc = 1.69
Help on Optical Data: Optical Data: Biaxial (+), a=1.665, b=1.672-1.676, g=1.684-1.686, bire=0.0190-0.0210, 2V(Calc)=76-86, 2V(Meas)=84-85. Dispersion strong, r > v.
Help on Pleochroism (x): Pleochroism (x): colorless or blue.
Help on Pleochroism (y): Pleochroism (y): colorless or yellow.

Calculated Properties of Lawsonite

Help on Electron Density: Electron Density: Bulk Density (Electron Density)=3.11 gm/cc
note: Specific Gravity of Lawsonite =3.09 gm/cc.
Help on Fermion Index: Fermion Index: Fermion Index = 0.0087662672
Boson Index = 0.9912337328
Help on Photoelectric: Photoelectric: PELawsonite = 2.77 barns/electron
U=PELawsonite x rElectron Density= 8.60 barns/cc.
Help on Radioactivity: Radioactivity: GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Lawsonite is Not Radioactive

Lawsonite Classification

Help on  Dana Class: Dana Class: (56)Sorosilicate Si2O7 Groups and O, OH, F. and H2O
  (56.02)with cations in [4] and/or >[4] coordination
  (56.02.03)Lawsonite - Ilvaite group Lawsonite CaAl2Si2O7(OH)2•(H2O) Ccmm 2/m 2/m 2/m Hennomartinite SrMn2Si2O7(OH)2•(H2O) C mcm 2/m 2/m 2/m Ilvaite CaFe2FeSi2O7O(OH) Pbnm 2/m 2/m 2/m Noelbensonite! BaMn2(Si2O7)(OH)2•(H2O) C mcm 2/m 2/m 2/m Itoigawaite! SrAl2Si2O7(OH)2•(H2O) C mcm 2/m 2/m 2/m Manganilvaite! CaFeFe(Mn,Fe)(Si2O7)O(OH) P 21/a 2/m
Help on  Strunz Class: Strunz Class: 09.BE.05 09 - SILICATES (Germanates)
  09.B - Sorosilicates
  09.BE -Si2O7 groups with additional anions;
09.BE.05 Hennomartinite SrMn2Si2O7(OH)2•(H2O) C mcm 2/m 2/m 2/m
09.BE.05 Lawsonite CaAl2Si2O7(OH)2•(H2O) Ccmm 2/m 2/m 2/m
09.BE.05 Noelbensonite! BaMn2(Si2O7)(OH)2•(H2O) C mcm 2/m 2/m 2/m
09.BE.05 Itoigawaite! SrAl2Si2O7(OH)2•(H2O) C mcm 2/m 2/m 2/m

Other Lawsonite Information

Help on See Also: See Also: Links to other databases for Lawsonite :
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 - Minerals in Thin Sections-Humboldt State
13 - Online Mineral Museum
14 - QUT Mineral Atlas
15 - Ruff.Info

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Dana No: Strunz No: 09.BE.05





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