Walkerite Mineral Data

General Walkerite Information

Chemical Formula:

Ca16(Mg,Li,[ ])2[B13O17(OH)12]4Cl6•28(H2O)

Composition:

Molecular Weight = 3,822.57 gm

Potassium 0.06 % K 0.07 % K₂O

Sodium 0.10 % Na 0.13 % Na₂O

Lithium 0.06 % Li 0.12 % Li₂O

Calcium 16.36 % Ca 22.89 % CaO

Magnesium 0.35 % Mg 0.58 % MgO

Iron 0.25 % Fe 0.32 % FeO

Boron 14.54 % B 46.83 % B₂O₃

Hydrogen 2.83 % H 25.28 % H₂O

Chlorine 4.88 % Cl 4.88 % Cl

- % Cl -1.10 % -O=Cl₂

Oxygen 60.58 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Ca_15.6Na_0.16K_0.06Mg_0.55Li_0.31Fe²⁺_0.17B_51.43O₆₈(OH)₄₈Cl_5.26(OH)_0.74H_2.53�28(H₂O)

Environment:

Upper Halite Member of the Windsor Group evaporites. Structure is similar to penobsquisite and pringleite.

IMA Status:

Approved IMA 2002 (Dana # Added)

Locality:

Potash Corporation of Saskatchewan (New Brunswick Division) mine at Penobsquis, near Sussex, Kings County, New Brunswick, Canada. Link to MinDat.org Location Data.

Name Origin:

Named for Thomas Leonard Walker (1867-1942), Founding Member and past president Geological Society of America.

Synonym:

IMA2001-051

Walkerite Image

Images:

Walkerite

Comments: Scanning electron micrograph of an acicular walkerite crystal.
Location: Potash Corporation of Saskatchewan (New Brunswick Division) mine at Penobsquis, near Sussex, Kings County, New Brunswick, Canada. Scale: See Picture.
© Canadian Mineralogist

Walkerite Crystallography

Axial Ratios:

a:b:c =0.6824:1:0.3852

Cell Dimensions:

a = 15.52, b = 22.74, c = 8.761, Z = 1; V = 3,091.97 Den(Calc)= 2.05

Crystal System:

Orthorhombic - Pyramidal H-M Symbol (mm2) Space Group: Pba2

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

By Intensity(I/I_o): 12.82(1)(110), 7.785(0.8)(200), 6.319(0.4)(121),2.57(0.3)(461,550), 3.17(0.3)(170), 5.649(0.3)(211), 2.413(0.2), 4.14(0.2), 6.8(0.2),

Physical Properties of Walkerite

Cleavage:

None

Color:

Colorless, White.

Density:

2.07

Diaphaneity:

Transparent to Translucent

Fracture:

Brittle - Splintery - Brittle fracture leaving splintery fragments.

Habit:

Acicular - Occurs as needle-like crystals.

Habit:

Fibrous - Crystals made up of fibers.

Hardness:

3 - Calcite

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Walkerite

Gladstone-Dale:

CI meas= -0.021 (Excellent) - where the CI = (1-KPDmeas/KC)
CI calc= -0.031 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2605,KPDmeas= 0.258,KC= 0.2526
Ncalc = 1.52

Optical Data:

Biaxial (+), a=1.516, b=1.532, g=1.554, bire=0.0380, 2V(Calc)=82, 2V(Meas)=82.2. Dispersion dispersion not observed.

Calculated Properties of Walkerite

Electron Density:

Bulk Density (Electron Density)=2.10 gm/cc
note: Specific Gravity of Walkerite =2.07 gm/cc.

Fermion Index:

Fermion Index = 0.02
Boson Index = 0.98

Photoelectric:

PE_Walkerite= 2.61 barns/electron
U=PE_Walkerite x r_electron= 5.49 barns/cc.

Radioactivity:

GRapi = 0.92 (Gamma Ray American Petroleum Institute Units)
Concentration of Walkerite per GRapi unit =108.97 (%)

Estimated Radioactivity from Walkerite - barely detectable

Walkerite Classification

Dana Class:

26.05.17.05 (26)Hydrated Borates Containing Hydroxyl or Halogen

(26.05)Dana Type

(26.05.17)Pringleite Group

26.05.17.01 Pringleite Ca9B26O34(OH)24Cl4•13(H2O) P1 1

26.05.17.02 Ruitenbergite Ca9B26O34(OH)24Cl4•13(H2O) P 2₁ 2

26.05.17.03 Brianroulstonite! Ca3[B5O6(OH)6](OH)Cl2•8(H2O) Pa m

26.05.17.04 Penobsquisite! Ca2Fe[B9O13(OH)6]Cl•4(H2O) P 2₁ 2

26.05.17.05 Walkerite! Ca16(Mg,Li,[])2[B13O17(OH)12]4Cl6•28(H2O) Pba2 mm2

Strunz Class:

06.GB.20 06 - BORATES

06.G - Heptaborates and other Megaborates

06.GB -Phyllo-nonborates, etc.

06.GB.20 Walkerite! Ca16(Mg,Li,[])2[B13O17(OH)12]4Cl6•28(H2O) Pba2 mm2

Other Walkerite Information

References:

NAME( CanMin, v 40, p 1675) PHYS. PROP.(CanMin, v 40, p 1675) OPTIC PROP.(CanMin, v 40, p 1675)

See Also:

Links to other databases for Walkerite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - GeoScienceWorld
4 - Google Images
5 - Google Scholar
6 - MinDAT
7 - Mineralienatlas (Deutsch)
8 - Online Mineral Museum
9 - QUT Mineral Atlas
10 - Ruff.Info

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Walkerite

Ca16(Mg,Li,[ ])2[B13O17(OH)12]4Cl6•28(H2O)
Dana No: 26.05.17.05 Strunz No: 06.GB.20
Locality:

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