Anorthoclase Mineral Data

General Anorthoclase Information

Chemical Formula:

(Na,K)AlSi3O8

Composition:

Molecular Weight = 266.25 gm

Potassium 3.67 % K 4.42 % K₂O

Sodium 6.48 % Na 8.73 % Na₂O

Aluminum 10.13 % Al 19.15 % Al₂O₃

Silicon 31.65 % Si 67.70 % SiO₂

Oxygen 48.07 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Na_0.75K_0.25AlSi₃O₈

Environment:

In high-temperature sodic volcanic and hypabyssal rocks.

IMA Status:

Valid Species (Pre-IMA) 1885

Locality:

Rather abundant worldwide. Some localities for well-characterized material include: on Pantelleria and Ustica Islands, Italy. At Larvik, Norway. From Berkum, North Rhine-Westphalia, Ge Link to MinDat.org Location Data.

Name Origin:

From the Greek for "oblique" and "fracture," descriptive of the cleavage

Name Pronunciation:

Anorthoclase + Pronunciation

Synonym:

ICSD 31180

PDF 9-478

Soda Microcline

Anorthoclase Image

Images:

Anorthoclase

Comments: Two white crystals of anorthoclase (possibly mislabeled and actually anorthite.
Location: Kusukidani, Wakayama Prefecture, Kinki Region, Honshu island, Japan. Scale: 15x14x6 mm.
© John Betts - Fine Minerals

Anorthoclase Crystallography

Axial Ratios:

a:b:c =0.6406:1:0.5546

Cell Dimensions:

a = 8.2, b = 12.8, c = 7.1, Z = 4; alpha = 90°, beta = 116°, gamma = 90° V = 669.80 Den(Calc)= 2.64

Crystal System:

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

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

By Intensity(I/I_o): 3.211(1), 3.243(0.9), 4.106(0.16),

Crystal Structure:

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Harlow G E , American Mineralogist , 67 (1982) p.975-996, The anorthoclase structures: The effects of temperature and composition, Grande Calderira, Or = 32.5, T = 23 deg C, feldspar

View Additional jPOWD Structure files for Anorthoclase
[1] [2] [3] [4] [5]

Physical Properties of Anorthoclase

Cleavage:

{001} Perfect, {010} Good

Color:

Colorless, Green, Gray, Gray pink, Yellow.

Density:

2.57 - 2.6, Average = 2.58

Diaphaneity:

Transparent

Fracture:

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

Habit:

Disseminated - Occurs in small, distinct particles dispersed in matrix.

Habit:

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

Hardness:

6 - Orthoclase

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Anorthoclase

Gladstone-Dale:

CI meas= 0.007 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= 0.027 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2001,KPDmeas= 0.2043,KC= 0.2057
Ncalc = 1.53 - 1.54

Optical Data:

Biaxial (-), a=1.519-1.529, b=1.524-1.534, g=1.527-1.536, bire=0.0070-0.0080, 2V(Calc)=64-74, 2V(Meas)=34-60. Dispersion r > v.

Pleochroism (x):

colorless.

Pleochroism (y):

colorless.

Pleochroism (z):

colorless.

Calculated Properties of Anorthoclase

Electron Density:

Bulk Density (Electron Density)=2.56 gm/cc
note: Specific Gravity of Anorthoclase =2.59 gm/cc.

Fermion Index:

Fermion Index = 0.01
Boson Index = 0.99

Photoelectric:

PE_Anorthoclase= 1.98 barns/electron
U=PE_Anorthoclase x r_electron= 5.08 barns/cc.

Radioactivity:

GRapi = 52.50 (Gamma Ray American Petroleum Institute Units)
Concentration of Anorthoclase per GRapi unit = 1.90 (%)

Estimated Radioactivity from Anorthoclase - barely detectable

Anorthoclase Classification

Dana Class:

76.01.01.06 (76)Tectosilicate Al-Si Framework

(76.01)with Al-Si frameworks

(76.01.01)K (Na,Ba) feldspars

76.01.01.01 Orthoclase KAlSi3O8 C 2/m 2/m

76.01.01.02 Sanidine (K,Na)(Si,Al)4O8 C 2/m 2/m

76.01.01.03 Hyalophane (K,Ba)Al(Si,Al)3O8 C 2/m 2/m

76.01.01.04 Celsian BaAl2Si2O8 I21/c 2/m

76.01.01.05 Microcline KAlSi3O8 C1 1

76.01.01.06 Anorthoclase (Na,K)AlSi3O8 C1 1

76.01.01.07 Rubicline! (Rb,K)AlSi3O8 P1 1

76.01.01.08 Filatovite! K[(Al,Zn)2(As,Si)2O8] I2/c 2/m

Strunz Class:

09.FA.30 09 - SILICATES (Germanates)

09.F - Tektosilicates without Zeolitic H2O

09.FA -Tektosilicates without additional non-tetrahedral anions, (Al,B):Si = 1:1

09.FA.30 Buddingtonite (NH4)AlSi3O8•0.5(H2O) P 2₁ or P 2₁/m Mono

09.FA.30 Celsian BaAl2Si2O8 I21/c 2/m

09.FA.30 Anorthoclase (Na,K)AlSi3O8 C1 1

09.FA.30 Hyalophane (K,Ba)Al(Si,Al)3O8 C 2/m 2/m

09.FA.30 Orthoclase KAlSi3O8 C 2/m 2/m

09.FA.30 Microcline KAlSi3O8 C1 1

09.FA.30 Rubicline! (Rb,K)AlSi3O8 P1 1

09.FA.30 Sanidine (K,Na)(Si,Al)4O8 C 2/m 2/m

Other Anorthoclase Information

References:

NAME( AntBidBlaNic2) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Heinrich65)

See Also:

Links to other databases for Anorthoclase :
1 - Alkali-Nuts(English)
2 - Alkali-Nuts(Francais)
3 - Am. Min. Crystal Structure Database
4 - Athena
5 - EUROmin Project
6 - Ecole des Mines de Paris
7 - Franklin Minerals(Dunn)
8 - GeoScienceWorld
9 - Google Images
10 - Google Scholar
11 - Handbook of Mineralogy (MinSocAm)
12 - Handbook of Mineralogy (UofA)
13 - MinDAT
14 - Mineral and Gemstone Kingdom
15 - Mineralienatlas (Deutsch)
16 - Online Mineral Museum
17 - QUT Mineral Atlas
18 - Ruff.Info
19 - UCLA - Petrography Thin-Sections
20 - WWW-MINCRYST

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

Anorthoclase

(Na,K)AlSi3O8
Dana No: 76.01.01.06 Strunz No: 09.FA.30
Locality:

Notes: