Oligoclase Mineral Data
General Oligoclase Information
Chemical Formula:
(Na,Ca)(Si,Al)4O8
Composition:
Molecular Weight = 265.42 gm
Sodium 6.93 % Na 9.34 % Na2 O
Calcium 3.02 % Ca 4.23 % CaO
Aluminum 12.20 % Al 23.05 % Al2 O3
Silicon 29.63 % Si 63.38 % SiO2
Oxygen 48.22 % O
______ ______
100.00 % 100.00 % = TOTAL OXIDE
Empirical Formula:
Na0.8 Ca0.2 Al1.2 Si2.8 O8
Environment:
Magmatic and pegmatitic rocks.
IMA Status:
Valid Species (Pre-IMA) 1826
Locality:
Twedestrand, Norway. Link to MinDat.org Location Data.
Name Origin:
From the Greek, oligos and kasein, "little cleavage."
Name Pronunciation:
Oligoclase + Pronunciation
Synonym:
Ab80
An20
Sunstone
Oligoclase Image
Images:
Images:
Oligoclase Crystallography
Axial Ratios:
a:b:c =0.6377:1:0.6651
Cell Dimensions:
a = 8.15, b = 12.78, c = 8.5, Z = 5; alpha = 94.016°, beta = 116.3333°, gamma = 88.667° V = 791.30 Den(Calc)= 2.78
Crystal System:
Triclinic - Pinacoidal H-M Symbol ( 1 ) Space Group: C1
X Ray Diffraction:
By Intensity(I/Io ): 3.2(1), 3.74(0.8), 4.02(0.8),
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Physical Properties of Oligoclase
Cleavage:
{001} Perfect, {010} Good
Color:
Brown, Colorless, Greenish, Gray, Yellowish.
Density:
2.64 - 2.66, Average = 2.65
Diaphaneity:
Transparent to Translucent
Fracture:
Uneven - Flat surfaces (not cleavage) fractured in an uneven pattern.
Habit:
Euhedral Crystals - Occurs as well-formed crystals showing good external form.
Habit:
Granular - Generally occurs as anhedral to subhedral crystals in matrix.
Hardness:
7 - Quartz
Luminescence:
Fluorescent, Long UV=yellow.
Luster:
Vitreous (Glassy)
Streak:
white
Optical Properties of Oligoclase
Gladstone-Dale:
CI meas = 0.007 (Superior) - where the CI = (1-KPDmeas /KC ) CI calc = 0.054 (Good) - where the CI = (1-KPDcalc /KC )
KPDcalc = 0.1951,KPDmeas = 0.2047,KC = 0.2062 Ncalc = 1.54 - 1.57
Optical Data:
Biaxial (+), a=1.533-1.543, b=1.5368-1.5477, g=1.542-1.552, bire=0.0090, 2V(Calc)=82-86, 2V(Meas)=82. Dispersion none.
Pleochroism (x):
colorless.
Pleochroism (y):
colorless.
Calculated Properties of Oligoclase
Electron Density:
Bulk Density (Electron Density)=2.63 gm/cc note: Specific Gravity of Oligoclase =2.65 gm/cc.
Fermion Index:
Fermion Index = 0.01 Boson Index = 0.99
Photoelectric:
PEOligoclase = 1.98 barns/electronU=PEOligoclase x r Electron Density= 5.19 barns/cc.
Radioactivity:
GRapi = 0 (Gamma Ray American Petroleum Institute Units) Oligoclase is Not Radioactive
Oligoclase Classification
Dana Class:
76.01.03.02 (76) Tectosilicate Al-Si Framework
(76.01) with Al-Si frameworks
(76.01.03) Plagioclase series
76.01.03.00 Plagioclase * (Na,Ca)(Si,Al)4O8 C1 1
76.01.03.01 Albite NaAlSi3O8 C1 1
76.01.03.02 Oligoclase (Na,Ca)(Si,Al)4O8 C1 1
76.01.03.03 Andesine * (Na,Ca)(Si,Al)4O8 C1 1
76.01.03.04 Labradorite * (Ca,Na)(Si,Al)4O8 C1 1
76.01.03.05 Bytownite * (Ca,Na)(Si,Al)4O8 C1 1
76.01.03.06 Anorthite CaAl2Si2O8 P1 ,I1 1
Strunz Class:
09.FA.35 09 - SILICATES (Germanates)
09.F - Tektosilicates without Zeolitic H2O
09.FA -Tektosilicates without additional non-tetrahedral anions, (Al,B):Si = 1:1
09.FA.35 Albite NaAlSi3O8 C1 1
09.FA.35 Bytownite * (Ca,Na)(Si,Al)4O8 C1 1
09.FA.35 Anorthite CaAl2Si2O8 P1 ,I1 1
09.FA.35 Andesine * (Na,Ca)(Si,Al)4O8 C1 1
09.FA.35 Labradorite * (Ca,Na)(Si,Al)4O8 C1 1
09.FA.35 Oligoclase (Na,Ca)(Si,Al)4O8 C1 1
09.FA.35 Reedmergnerite NaBSi3O8 C1 1
09.FA.35 Plagioclase * (Na,Ca)(Si,Al)4O8 C1 1
Other Oligoclase Information
See Also:
Links to other databases for Oligoclase :
1 - Alkali-Nuts(English)
2 - Alkali-Nuts(Francais)
3 - Am. Min. Crystal Structure Database
4 - Amethyst Galleries' Mineral Gallery
5 - Athena
6 - EUROmin Project
7 - Ecole des Mines de Paris
8 - Franklin Minerals(Dunn)
9 - GeoScienceWorld
10 - Glendale Community College
11 - Google Images
12 - Google Scholar
13 - Handbook of Mineralogy (MinSocAm)
14 - Handbook of Mineralogy (UofA)
15 - HyperPhysics
16 - MinDAT
17 - Mineral and Gemstone Kingdom
18 - Mineralienatlas (Deutsch)
19 - Online Mineral Museum
20 - Philatelic Mineralogy
21 - QUT Mineral Atlas
22 - Ruff.Info
23 - Scandinavian mineral gallery
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Oligoclase
(Na,Ca)(Si,Al)4O8
Dana No: 76.01.03.02 Strunz No: 09.FA.35
Locality:
Notes:
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