Bytownite Mineral Data

Bytownite Mineral Data +

General Bytownite Information

Chemical Formula:

(Ca,Na)(Si,Al)4O8

Composition:

Molecular Weight = 275.01 gm

Sodium 1.67 % Na 2.25 % Na₂O

Calcium 11.66 % Ca 16.31 % CaO

Aluminum 17.66 % Al 33.37 % Al₂O₃

Silicon 22.47 % Si 48.07 % SiO₂

Oxygen 46.54 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Na_0.2Ca_0.8Al_1.8Si_2.2O₈

Environment:

Magmatic and metamorphic rocks.

IMA Status:

Not Approved IMA 1835

Locality:

"Bytown," now Ottawa, Ontario, Canada. Link to MinDat.org Location Data.

Name Origin:

Named after its locality.

Synonym:

Ab20

An80

ICSD 34791

PDF 41-1481

Bytownite Image

Images:

Bytownite Plagioclase

Comments: Translucent crystalline bytownite.
Location: Crystal Bay, Hennepin County, Minnesota, USA. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Bytownite Crystallography

Axial Ratios:

a:b:c =0.6357:1:1.0241

Cell Dimensions:

a = 8.17, b = 12.85, c = 13.16, Z = 7; alpha = 93.5°, beta = 116.016°, gamma = 90.833° V = 1,239.15 Den(Calc)= 2.58

Crystal System:

Triclinic - PinacoidalH-M Symbol ( 1) Space Group: C1

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

By Intensity(I/I_o): 3.2(1), 3.75(0.8), 4.03(0.8),

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Forms: [ 0 0 1] [ 1 0 0] [ 1 0 1] [ 0 1 0]

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Physical Properties of Bytownite

Cleavage:

[001] Perfect, [010] Good

Color:

Colorless, Gray, White.

Density:

2.7 - 2.72, Average = 2.71

Diaphaniety:

Translucent to transparent

Fracture:

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

Habit:

Crystalline - Coarse - Occurs as well-formed coarse sized crystals.

Habit:

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

Habit:

Striated - Parallel lines on crystal surface or cleavage face.

Hardness:

7 - Quartz

Luminescence:

Non-fluorescent.

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Bytownite

Gladstone-Dale:

CI meas= -0.018 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= -0.07 (Fair) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2221,KPDmeas= 0.2114,KC= 0.2076

Optical Data:

Biaxial (+/-), a=1.563-1.572, b=1.568-1.5784, g=1.573-1.583, bire=0.0100-0.0110, 2V(Calc)=80-88, 2V(Meas)=86.

Pleochroism (x):

colorless.

Pleochroism (y):

colorless.

Pleochroism (z):

colorless.

Calculated Properties of Bytownite

Electron Density:

r_electron=2.69 gm/cc
note: r_Bytownite=2.71 gm/cc.

Fermion Index

Fermion Index = 0.01087
Boson Index = 0.98913

Photoelectric:

PE_Bytownite= 2.84 barns/electron
U=PE_Bytownite x r_electron= 7.64 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Bytownite is Not Radioactive

Bytownite Classification

Dana Class:

76.1.3.5 (76)Tectosilicate Al-Si Framework

(76.1)with Al-Si frameworks

(76.1.3)Plagioclase series

76.1.3.0 Plagioclase* (Na,Ca)(Si,Al)4O8 C1 1

76.1.3.1 Albite NaAlSi3O8 C1 1

76.1.3.2 Oligoclase (Na,Ca)(Si,Al)4O8 C1 1

76.1.3.3 Andesine* (Na,Ca)(Si,Al)4O8 C1 1

76.1.3.4 Labradorite* (Ca,Na)(Si,Al)4O8 C1 1

76.1.3.5 Bytownite * (Ca,Na)(Si,Al)4O8 C1 1

76.1.3.6 Anorthite CaAl2Si2O8 P1,I1 1

Strunz Class:

VIII/J.07-60 VIII - Silicates

VIII/J - Tectosilicates (network) without anions unfamiliar to the tetraheders

VIII/J.07 - Feldspar group, Anorthoclase - Anorthite - Banalcite series

VIII/J.07-10 Anorthoclase (Na,K)AlSi3O8 C1 1

VIII/J.07-20 Albite NaAlSi3O8 C1 1

VIII/J.07-30 Oligoclase (Na,Ca)(Si,Al)4O8 C1 1

VIII/J.07-40 Andesine* (Na,Ca)(Si,Al)4O8 C1 1

VIII/J.07-50 Labradorite* (Ca,Na)(Si,Al)4O8 C1 1

VIII/J.07-60 Bytownite (Ca,Na)(Si,Al)4O8 C1 1

VIII/J.07-70 Anorthite CaAl2Si2O8 P1,I1 1

VIII/J.07-75 Dmisteinbergite CaAl2Si2O8 P 6/mmm 6/m 2/m 2/m

VIII/J.07-80 Svyatoslavite CaAl2Si2O8 P 2₁ 2

VIII/J.07-90 Stronalsite SrNa2Al4Si4O16 I bam,Iba2 Ortho

VIII/J.07-100 Banalsite BaNa2Al4Si4O16 I bam 2/m 2/m 2/m

VIII/J.07-110 Filatovite! K[(Al,Zn)2(As,Si)2O8] I2/c 2/m

Other Bytownite Information

References:

NAME( Sinkankas66) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Heinrich65)

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Bytownite

(Ca,Na)(Si,Al)4O8
Dana No: 76.1.3.5 Strunz No: VIII/J.07-60
Locality:

Notes: