Plagioclase Mineral Data (original) (raw)

General Plagioclase Information

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.

Name Pronunciation:

Plagioclase + Pronunciation

Plagioclase Image

Images:

	Plagioclase Albite 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

Images:

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

Images:

	Plagioclase Labradorite 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

Images:

Plagioclase Crystallography

Crystal System:

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

Physical Properties of Plagioclase

Cleavage:

{001} Good, {010} Good

Color:

White, Gray, Bluish white, Reddish white, Greenish white.

Density:

2.61 - 2.76, Average = 2.68

Diaphaneity:

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

Optical Data:

NCalc= 1.56 - from Gladstone-Dale relationship (KC = 0.2101) where Ncalc=Dmeas*KC+1

Calculated Properties of Plagioclase

Electron Density:

Bulk Density (Electron Density)=2.67 gm/cc
note: Specific Gravity of Plagioclase =2.69 gm/cc.

Fermion Index:

Fermion Index = 0.01
Boson Index = 0.99

Photoelectric:

PEPlagioclase = 2.46 barns/electron
U=PEPlagioclase x rElectron Density= 6.56 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Plagioclase is Not Radioactive

Plagioclase Classification

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

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

References:

NAME( Duda&Rejl90) PHYS. PROP.(Duda&Rejl90)

Search for Plagioclase using:

[AOL] [Bing] [Dog Pile] [GeoScienceWorld] [HotBot] [Ixquick] [Lycos] [MAMMA] [Scirus] [Teoma] [WebCrawler] [Wikipedia] [YAHOO]

Visit our Advertisers for Plagioclase :

A Bijoux Google Search for Plagioclase
Adam's Minerals Google Search for Plagioclase
Cape Minerals Google Search for Plagioclase
Dakota Matrix Minerals Google Search for Plagioclase
Excalibur Mineral Corp. Google Search for Plagioclase
Exceptional Minerals Google Search for Plagioclase
John Betts Fine Minerals Search for Plagioclase
McDougall Minerals Google Search for Plagioclase
Mineral News Website Link
Rock and Mineral Shows Google Search for Plagioclase
Weinrich Minerals, Inc. Google Search for Plagioclase

Ask about Plagioclase here :
Ask-A-Mineralogist from the Mineralogical Society of America
Mindat.org's Discussion Groups
Original Rockhounds Discussion Group
Rockhounds Discussion Group on Yahoo Groups
Mineral Discussion Forum from Fabre Minerals - also available in Espa�ol

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: