Mineralogy Database

Plagioclase Mineral Data

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General Plagioclase Information

Help on Chemical  Formula: Chemical Formula: (Na,Ca)(Si,Al)4O8
Help on Composition: 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
Help on Empirical Formula: Empirical Formula: Na0.5Ca0.5Si3AlO8
Help on Environment: Environment: Igneous and metamorphic rocks. Group name for Na, Ca feldspars.
Help on IMA Status: IMA Status: Not Approved IMA
Help on Locality: Locality: Common world wide occurrences. Link to MinDat.org Location Data.
Help on Name Origin: Name Origin: From the Greek plagios - "oblique" and klao - "I cleave" in allusion to the obtuse cleavage angles of the good cleavages.
Help on Name Pronunciation: Name Pronunciation: Plagioclase + Pronunciation Say PLAGIOCLASE
 

Plagioclase Image

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  Albite   Plagioclase

Comments: Colorless, lustrous blocky albite crystals to 3 cm in size with a thick dusting of micaceous green micro chlorite.
Location: Acushnet Quarry, Bristol Co., Massachussetts, USA. Scale: 17 x 15 x 7.5 cm matrix.
© Dan Weinrich

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  Albite   Plagioclase

Comments: Crystal group of bladed albite (variety cleavelandite) crystals.
Location: Taquaral, Minas Gerais, Brazil. Scale: 7.4 x 5 cm.
© John Veevaert

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  Labradorite   Plagioclase

Comments: Dual view of a cleavage fragment of labradorite showing the multi-colored labradorescence (schiller effect) and the same area viewed without the color. The color is due to optical interference on Bøggild exsolution lamellae.
Location: Ihosy, Betroka district, Toliara Province, Madagascar. Scale: Picture size 3x3 cm.
© Dave Barthelmy

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  Oligoclase   Plagioclase

Comments: Rectangular cleavage fragment of salmon-orange oligoclase (sunstone) feldspar.
Location: Norway. Scale: 47x30x7 mm.
© John Betts - Fine Minerals

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  Anorthite   Plagioclase

Comments: Opaque white crystal of anorthite with dark brown solidified lava coating.
Location: Miyake-jima, Shizuoka, Japan. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

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  Andesine   Plagioclase

Comments: Translucent andesine crystal twin.
Location: Maeyama Ueda shi, Nagano, Japan. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

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  Bytownite   Plagioclase

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

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  Oligoclase   Plagioclase

Comments: Clear glassy crystalline oligoclase with milky quartz and muscovite.
Location: Bakersville, Mitchell County, North Carolina, USA. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

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  Plagioclase

Comments: Plagioclase, variety kenyite, crystals in volcanic rock.
Location: Kirinyaga (Mount Kenya), Central Province, Kenya. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Plagioclase Crystallography

Help on Crystal System: Crystal System: Triclinic - Pinacoidal H-M Symbol ( 1) Space Group: C1
 

Physical Properties of Plagioclase

Help on Cleavage: Cleavage: {001} Good, {010} Good
Help on Color: Color: White, Gray, Bluish white, Reddish white, Greenish white.
Help on Density: Density: 2.61 - 2.76, Average = 2.68
Help on Diaphaneity: Diaphaneity: Transparent to translucent
Help on Fracture: Fracture: Brittle - Generally displayed by glasses and most non-metallic minerals.
Help on Habit: Habit: Massive - Granular - Common texture observed in granite and other igneous rock.
Help on Hardness: Hardness: 6-6.5 - Orthoclase-Pyrite
Help on Luminescence: Luminescence: Non-fluorescent.
Help on Luster: Luster: Vitreous (Glassy)
Help on Streak: Streak: white
 

Optical Properties of Plagioclase

Help on Optical Data: Optical Data: NCalc= 1.56 - from Gladstone-Dale relationship (KC = 0.2101) where Ncalc=Dmeas*KC+1
 

Calculated Properties of Plagioclase

Help on Electron Density: Electron Density: Bulk Density (Electron Density)=2.67 gm/cc
note: Specific Gravity of Plagioclase =2.69 gm/cc.
Help on Fermion Index: Fermion Index: Fermion Index = 0.01
Boson Index = 0.99
Help on Photoelectric: Photoelectric: PEPlagioclase = 2.46 barns/electron
U=PEPlagioclase x rElectron Density= 6.56 barns/cc.
Help on Radioactivity: Radioactivity: GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Plagioclase is Not Radioactive
 

Plagioclase Classification

Help on  Dana Class: Dana Class: 76.01.03.00 (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
Help on  Strunz Class: 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 Plagioclase Information

Help on References: References: NAME( Duda&Rejl90) PHYS. PROP.(Duda&Rejl90)
Help on See Also: See Also: Links to other databases for Plagioclase :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - CalTech Mineral Spectroscopy
4 - GeoScienceWorld
5 - Google Images
6 - Google Scholar
7 - HyperPhysics
8 - MinDAT
9 - Mineral and Gemstone Kingdom
10 - Mineralienatlas (Deutsch)
11 - Minerals in Thin Section-University of North Carolina
12 - Minerals in Thin Sections-Humboldt State
13 - Online Mineral Museum
14 - QUT Mineral Atlas
15 - Ruff.Info
16 - UCLA - Petrography Thin-Sections
17 - WWW-MINCRYST

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

Plagioclase

(Na,Ca)(Si,Al)4O8
Dana No: 76.01.03.00 Strunz No: 09.FA.35
Locality:

 

Notes:

 

 
   
 


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