Walstromite Mineral Data

Walstromite Mineral Data +

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General Walstromite Information

Chemical Formula:

BaCa2Si3O9

Composition:

Molecular Weight = 445.73 gm

Barium 30.81 % Ba 34.40 % BaO

Calcium 17.98 % Ca 25.16 % CaO

Silicon 18.90 % Si 40.44 % SiO₂

Oxygen 32.31 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

BaCa₂Si₃O₉

Environment:

Metamorphosed metasediments.

IMA Status:

Approved IMA 1965

Locality:

Big Creek - Rush Creek sanbornite deposit, 5 miles NE of Trimmer, Fresno Co., California. Link to MinDat.org Location Data.

Name Origin:

Named for Robert E. Walstrom (1920-), American mineral collector, who discovered the mineral.

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Walstromite Crystallography

Axial Ratios:

a:b:c =0.6991:1:0.7001

Cell Dimensions:

a = 6.723, b = 9.616, c = 6.733, Z = 2; alpha = 83.1°, beta = 77.67°, gamma = 69.62° V = 395.73 Den(Calc)= 3.74

Crystal System:

Triclinic - PinacoidalH-M Symbol ( 1) Space Group: P1

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

By Intensity(I/I_o): 2.99(1), 2.7(0.2), 6.58(0.2),

Crystal Structure:

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Dent Glasser L S , Glasser F P , American Mineralogist , 53 (1968) p.9-13, The crystal structure of walstromite

Physical Properties of Walstromite

Cleavage:

[011] Perfect, [010] Perfect, [100] Very Good

Color:

Colorless, White.

Density:

3.67

Diaphaniety:

Transparent

Habit:

Granular - Generally occurs as anhedral to subhedral crystals in matrix.

Hardness:

3.5 - Copper Penny

Luminescence:

Fluorescent, Short UV=pale pink, Long UV=pinkish orange.

Luster:

Vitreous - Pearly

Streak:

white

Optical Properties of Walstromite

Gladstone-Dale:

CI meas= -0.022 (Excellent) - where the CI = (1-KPDmeas/KC)
CI calc= -0.003 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1816,KPDmeas= 0.185,KC= 0.181

Optical Data:

Biaxial (-), a=1.668, b=1.684, g=1.685, bire=0.0170, 2V(Calc)=26, 2V(Meas)=30. Dispersion weak.

Pleochroism (x):

colorless.

Pleochroism (y):

colorless.

Pleochroism (z):

colorless.

Calculated Properties of Walstromite

Electron Density:

r_electron=3.52 gm/cc
note: r_Walstromite=3.74 gm/cc.

Fermion Index

Fermion Index = 0.06413
Boson Index = 0.93587

Photoelectric:

PE_Walstromite= 134.15 barns/electron
U=PE_Walstromite x r_electron= 472.77 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Walstromite is Not Radioactive

Walstromite Classification

Dana Class:

59.1.2.1 (59)Cyclosilicate Three-Membered Rings

(59.1)anhydrous, no other anions

(59.1.2)Walstromite group

59.1.2.1 Walstromite BaCa2Si3O9 P1 1

59.1.2.2 Margarosanite Pb(Ca,Mn)2Si3O9 P1 1

Strunz Class:

VIII/E.02-10 VIII - Silicates

VIII/E - Cyklosilicates, triplet rings [Si3O9]6-

VIII/E.02 - Walstromite - Mathewrogersite series

VIII/E.02-10 Walstromite BaCa2Si3O9 P1 1

VIII/E.02-20 Margarosanite Pb(Ca,Mn)2Si3O9 P1 1

VIII/E.02-30 Roeblingite Pb2Ca6(Si6O18)(SO4)2(OH)2·4(H2O) C 2/m 2/m

VIII/E.02-40 Mathewrogersite Pb7(Fe,Cu)Al3GeSi12O36·(OH,H2O)6 R 3,R 3-,R 32,R 3m,R 3m- Trig

Other Walstromite Information

References:

NAME( Dana8) PHYS. PROP.(Dana8) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)

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

Walstromite

BaCa2Si3O9
Dana No: 59.1.2.1 Strunz No: VIII/E.02-10
Locality:

Notes: