Plagioclase Mineral Data + 
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- 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
General Plagioclase Information |
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 Chemical Formula: |
(Na,Ca)(Si,Al)4O8 | ||
| Composition: |
Molecular Weight = 270.77 gm | ||
| Sodium 4.25 % Na 5.72 % Na2O | |||
| Calcium 7.40 % Ca 10.36 % CaO | |||
| Aluminum 9.96 % Al 18.83 % Al2O3 | |||
| Silicon 31.12 % Si 66.57 % SiO2 | |||
| Oxygen 47.27 % O | |||
| ______ ______ | |||
| 100.00 % 101.48 % = TOTAL OXIDE | |||
| Empirical Formula: |
Na0.5Ca0.5Si3AlO8 | ||
| Environment: |
Igneous and metamorphic rocks. Group name for Na, Ca feldspars. | ||
| IMA Status: |
Not Approved IMA | ||
| Locality: |
Common world wide occurrences. Link to MinDat.org Location Data. | ||
| Name Origin: |
From the Greek plagios - "oblique" and klao - "I cleave" in allusion to the obtuse cleavage angles of the good cleavages. | ||
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Plagioclase Crystallography |
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| Crystal System: |
Triclinic - PinacoidalH-M Symbol ( 1) Space Group: C1 | ||
Physical Properties of Plagioclase |
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| Cleavage: |
[001] Good, [010] Good | ||
| Color: |
White, Gray, Bluish white, Reddish white, Greenish white. | ||
| Density: |
2.61 - 2.76, Average = 2.68 | ||
| Diaphaniety: |
Transparent to translucent | ||
| Fracture: |
Brittle - Generally displayed by glasses and most non-metallic minerals. | ||
| Habit: |
Massive - Granular - Common texture observed in granite and other igneous rock. | ||
| Hardness: |
6-6.5 - Orthoclase-Pyrite | ||
| Luminescence: |
Non-fluorescent. | ||
| Luster: |
Vitreous (Glassy) | ||
| Streak: |
white | ||
Optical Properties of Plagioclase |
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| Optical Data: |
NCalc= 1.56 - from Gladstone-Dale relationship (KC = 0.2101) where Ncalc=Dmeas*KC+1 | ||
Calculated Properties of Plagioclase |
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| Electron Density: |
relectron=2.67 gm/cc |
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| Fermion Index |
Fermion Index = 0.01485 Boson Index = 0.98515 |
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| Photoelectric: |
PEPlagioclase = 2.46 barns/electron |
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| Radioactivity: |
GRapi = 0 (Gamma Ray American Petroleum Institute Units) Plagioclase is Not Radioactive |
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Plagioclase Classification |
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| Dana Class: |
76.1.3.0 (76)Tectosilicate Al-Si Framework | ||
| (76.1)with Al-Si frameworks | |||
| (76.1.3)Plagioclase series | |||
| Strunz Class: |
VIII/J.07-00 VIII - Silicates | ||
| VIII/J - Tectosilicates (network) without anions unfamiliar to the tetraheders | |||
| VIII/J.07 - Feldspar group, Anorthoclase - Anorthite - Banalcite series | |||
Other Plagioclase Information |
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| References: |
NAME( Duda&Rejl90) PHYS. PROP.(Duda&Rejl90) | ||
| See Also: |
Links to other databases for Plagioclase : 1 -Am. Min. Crystal Structure Database 2 -Athena 3 - CalTech Mineral Spectroscopy 4 -Google Images 5 -Google Scholar 6 - HyperPhysics 7 -MinDAT 8 -MinMax(Deutsch) 9 -MinMax(English) 10 - Mineral and Gemstone Kingdom 11 -Mineralienatlas (Deutsch) 12 - Minerals in Thin Section-University of North Carolina 13 -Minerals in Thin Sections-Humboldt State 14 -QUT Mineral Atlas 15 - Thin Sections - Brock University 16 - UCLA - Petrography Thin-Sections 17 -University of Minnesota 18 - WWW-MINCRYST Search for Plagioclase using: Visit our Advertisers for Plagioclase : Translate Plagioclase Mineral Data : Ask about Plagioclase here : Print or Cut-and-Paste your Plagioclase Specimen Label here :
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