Anorthoclase
A variety of Albite
This page kindly sponsored by John Kashuba
About Anorthoclase
Formula:
(Na,K)AlSi3O8
Colour:
white, colourless, greyish pink
Hardness:
6 - 6½
Crystal System:
Triclinic
Member of:
Name:
Named in 1885 by Karl Harry Ferdinand Rosenbusch from the Greek αν, ορθός and κλάσις, meaning "not right cleavage", descriptive of the mineral's cleavage.
First Recorded Locality:
A variety of Albite
Feldspar Group.
Anorthoclase is strictly a K-rich variety of albite. It was long used (and still is by petrologists) as an intermediate member of the high albite – sanidine (alkali feldspar) solid solution series, in which the albite member exists in larger proportion. It was defined based partly on optics, for compositions between 10 and 36 percent of KAlSi3O8 and between 64 and 90 percent of NaAlSi3O8. It occurs in high-temperature sodic volcanic and hypabyssal rocks.
Members of this series (high albite, anorthoclase and sanidine) are stable at temperatures of 400 °C and above. Below 400°C only very limited solution exists (less than about 5% on both the low albite and microcline ends). Anorthoclase and high albite exhibit triclinic symmetry, whereas sanidine and the medium temperature orthoclase have monoclinic symmetry. If the high temperature, intermediate composition alkali feldspars are allowed to cool slowly, exsolution occurs and a perthite structure results.
Compare Unnamed (New Ordered Member of the Alkali Feldspar Series) - an ordered K-Na feldspar.
Visit gemdat.org for gemological information about Anorthoclase.
Feldspar Group.
Anorthoclase is strictly a K-rich variety of albite. It was long used (and still is by petrologists) as an intermediate member of the high albite – sanidine (alkali feldspar) solid solution series, in which the albite member exists in larger proportion. It was defined based partly on optics, for compositions between 10 and 36 percent of KAlSi3O8 and between 64 and 90 percent of NaAlSi3O8. It occurs in high-temperature sodic volcanic and hypabyssal rocks.
Members of this series (high albite, anorthoclase and sanidine) are stable at temperatures of 400 °C and above. Below 400°C only very limited solution exists (less than about 5% on both the low albite and microcline ends). Anorthoclase and high albite exhibit triclinic symmetry, whereas sanidine and the medium temperature orthoclase have monoclinic symmetry. If the high temperature, intermediate composition alkali feldspars are allowed to cool slowly, exsolution occurs and a perthite structure results.
Compare Unnamed (New Ordered Member of the Alkali Feldspar Series) - an ordered K-Na feldspar.
Visit gemdat.org for gemological information about Anorthoclase.Unique Identifiers
Mindat ID:
248 (as Anorthoclase)
96 (as Albite)
96 (as Albite)
Long-form identifier:
mindat:1:1:248:4 (as Anorthoclase)
mindat:1:1:96:9 (as Albite)
mindat:1:1:96:9 (as Albite)
GUID
(UUID V4):
(UUID V4):
0e0be8a1-e639-4229-bf3b-49edfef26c5d (as Anorthoclase)
eee48ae9-e84f-4983-ae14-22ad58212555 (as Albite)
eee48ae9-e84f-4983-ae14-22ad58212555 (as Albite)
IMA Classification of Anorthoclase
IMA status notes:
Intermediate member of a solid-solution series
Approval history:
Listed in Whitney (2010) as intermediate.
Classification of Anorthoclase
76.1.1.6
76 : TECTOSILICATES Al-Si Framework
1 : Al-Si Framework with Al-Si frameworks
76 : TECTOSILICATES Al-Si Framework
1 : Al-Si Framework with Al-Si frameworks
16.4.4
16 : Silicates Containing Aluminum and other Metals
4 : Aluminosilicates of Na and K
16 : Silicates Containing Aluminum and other Metals
4 : Aluminosilicates of Na and K
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
Please only use the official IMA–CNMNC symbol. Older variants are listed for historical use only.
| Symbol | Source | Reference |
|---|---|---|
| Ano | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
| Ano | Whitney & Evans (2010) | Whitney, D.L. and Evans, B.W. (2010) Abbreviations for names of rock-forming minerals. American Mineralogist, 95, 185–187 doi:10.2138/am.2010.3371 |
| Anr | The Canadian Mineralogist (2019) | The Canadian Mineralogist (2019) The Canadian Mineralogist list of symbols for rock- and ore-forming minerals (December 30, 2019). download |
Physical Properties of Anorthoclase
Optical Data of Anorthoclase
Type:
Biaxial (-)
RI values:
nα = 1.519 - 1.529 nβ = 1.524 - 1.534 nγ = 1.527 - 1.536
2V:
Measured: 34° to 60°, Calculated: 64° to 74°
Max Birefringence:
δ = 0.008
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
and does not take into account mineral colouration.
Surface Relief:
Low
Dispersion:
r > v
Chemistry of Anorthoclase
Mindat Formula:
(Na,K)AlSi3O8
Common Impurities:
Fe,Ca
Crystallography of Anorthoclase
Crystal System:
Triclinic
Cell Parameters:
a = 8.28 Å, b = 12.97 Å, c = 7.15 Å
α = 91.05°, β = 116.26°, γ = 90.15°
α = 91.05°, β = 116.26°, γ = 90.15°
Ratio:
a:b:c = 0.638 : 1 : 0.551
Unit Cell V:
688.44 ų (Calculated from Unit Cell)
X-Ray Powder Diffraction
Image Loading
Radiation - Copper Kα
Data courtesy of RRUFF project at University of Arizona, used with permission.
First Recorded Occurrence of Anorthoclase
Synonyms of Anorthoclase
Other Language Names for Anorthoclase
French:Anorthose
German:Anorthoklas
Rhyakolith (in part)
Ryakolith (in part)
Rhyakolith (in part)
Ryakolith (in part)
Norwegian:Natron-orthoklas
Russian:Анортоклаз
Varieties of Anorthoclase
| Analbite (of Winchell) | Anorthoclase with less than 10% KAlSi3O8 |
| Anorthoclase-Sanidine | Feldspar Group. An unnecessary name for a variety of Anorthoclase with the tabular habit of sanidine but the optical extinction of Anorthoclase. Originally reported from Drachenfels, Königswinter, Siebengebirge, North Rhine-Westphalia, Germany. |
Relationship of Anorthoclase to other Species
Member of:
Other Members of this group:
| Ferrisanidine | K[Fe3+Si3O8] | Mon. 2/m : B2/m |
| K Feldspar | Potassium-dominant feldspars with variable crystal symmetry and Al-Si ordering state; they are a subgroup of ... | |
| Rubicline | Rb(AlSi3O8) | Mon. 2/m : B2/m |
Common Associates
Associated Minerals Based on Photo Data:
| 17 photos of Anorthoclase associated with Aegirine | NaFe3+Si2O6 |
| 9 photos of Anorthoclase associated with Augite | (CaxMgyFez)(Mgy1Fez1)Si2O6 |
| 8 photos of Anorthoclase associated with Ilmenite | Fe2+TiO3 |
| 7 photos of Anorthoclase associated with Kenyaite | Na2Si22O41(OH)8 · 6H2O |
| 5 photos of Anorthoclase associated with Quartz | SiO2 |
| 4 photos of Anorthoclase associated with Moonstone | |
| 3 photos of Anorthoclase associated with Arfvedsonite | [Na][Na2][Fe2+4Fe3+]Si8O22(OH)2 |
| 3 photos of Anorthoclase associated with Zircon | Zr(SiO4) |
| 3 photos of Anorthoclase associated with Ferrosilite | Fe2+2Si2O6 |
| 2 photos of Anorthoclase associated with Apatite | Ca5(PO4)3(Cl/F/OH) |
Other Information
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Anorthoclase in petrology
An essential component of rock names highlighted in red, an accessory component in rock names highlighted in green.
Internet Links for Anorthoclase
mindat.org URL:
https://www.mindat.org/min-248.html
Please feel free to link to this page.
Please feel free to link to this page.
Search Engines:
Mineral Dealers:
References for Anorthoclase
Reference List:
Localities for Anorthoclase
symbol to view information about a locality.
The Locality List
- This locality has map coordinates listed.
- This locality has estimated coordinates.
ⓘ - Click for references and further information on this occurrence.
? - Indicates mineral may be doubtful at this locality.
- Good crystals or important locality for species.
- World class for species or very significant.
(TL) - Type Locality for a valid mineral species.
(FRL) - First Recorded Locality for everything else (eg varieties).
All localities listed without proper references should be considered as questionable.
Afghanistan | |
| Merkel et al. (2013) |
Algeria | |
| Allègre et al. (1981) +4 other references |
| apports des donnees radiometriques (K/Ar) +6 other references | |
| M. Girod |
| M. Girod | |
Angola | |
| Andrade (note preliminaire) +2 other references |
| Eur. J. Mineral. +7 other references |
Antarctica | |
| Hamilton (1972) +1 other reference |
| Proceedings of the VII International ... +1 other reference | |
| Harrington et al. (1967) +1 other reference | |
| Gair (1967) +1 other reference | |
| Armienti et al. (1991) | |
| Goldschmidt Conference Abstracts 2005 | |
| Dov Bahat (1979) +2 other references |
| Cooper et al. (2007) | |
| Woolley (2019) | |
| LeMasurier (1990) |
| Boudette et al. (1966) +2 other references |
| Woolley (2019) |
| LeMasurier (1990) |
| Adie (Ed.) | |
Argentina | |
| ARAGON |
Armenia | |
| Bowell et al. (2021) |
Atlantic Ocean | |
| Carman et al. (South Atlantic) +1 other reference |
Australia | |
| Wellman et al. (1974) +1 other reference |
| Duggan +4 other references |
| Knutson +4 other references |
| Page (2011) |
| Dunn et al. (2007) | |
| Matthew Goodwin |
| Duggan (1990) | |
| Pearson et al. (1991) |
| R. Wally Johnson +3 other references |
| Stephenson (1989) |
| Stephenson (1989) | |
| Irving (1980) +3 other references | |
| De Keyser et al. (1968) +2 other references |
| Stolz (1987) | |
| McKay et al. (2001) |
| ROSS et al. (1987) |
| Stevens +3 other references |
| Bryan et al. (1973) +3 other references | |
| Bottrill et al. (2008) |
| Unpub data |
| Bottrill et al. (2020) |
| Everard |
| Taheri +1 other reference |
| |
| Museum Victoria collection +1 other reference |
| Museum Victoria Mineralogy Collection +1 other reference | |
| Judy Rowe collection | |
| |
| |
| |
| - (n.d.) | |
| Dov Bahat (1979) |
| Museum Victoria Mineralogy Collection |
| W.D.Birch +1 other reference |
| Museum Victoria Mineralogy Collection +1 other reference |
| Sutton & Mills (2012) |
| Dov Bahat (1979) |
| Dov Bahat (1979) | |
| Dov Bahat (1979) | |
| Edwards (1938) +6 other references | |
| Museum Victoria collection |
| Museum Victoria collections |
Austria | |
| U. Kolitsch et al. (2009) |
| Exel (1993) |
| |
| Alker (1956) |
Brazil | |
| Mineralogical Magazine 1998 62 : ... |
| Geological Survey Professional Paper 327 (U.S. Department of the Interior, 1959) |
| Guarino et al. (2021) |
| Salgado et al. (2019) |
Cameroon | |
| Lasserre +5 other references |
| Jérémine (1941) +6 other references |
| Jérémine (1943) +2 other references | |
Canada | |
| Am. Min. 59 |
| Peatfield (n.d.) |
| Peatfield (n.d.) | |
| GSC locality database |
| GSC locality database +1 other reference |
| Sabina (2000) |
| Schilling et al. (2011) |
| Eur. J. Mineral. |
Cape Verde | |
| Kogarko (1993) +3 other references |
Chad | |
| Vincent (Sahara du Tchad) +9 other references |
Chile | |
| Bailey et al. (1970) +4 other references |
China | |
| Shijin Xu et al. (2003) |
| Orris et al. (2002) |
| Song et al. (1989) +4 other references |
| Jiaxiang Qiu and Qun'an Liao (1990) +2 other references |
| Zhang et al. (2002) +1 other reference |
| Ogura +5 other references |
| GUANG-HONG et al. (1990) +3 other references |
| Zhenhua Ding (1998) |
| Da-Xin Li and Yi-Ming Zhao (1997) |
| Xiao Huiliang et al. (2003) +1 other reference |
| Chen et al. (2014) |
| Deng et al. (2024) |
| Daxian Zhao (1989) |
Cuba | |
| Yin et al. (2021) |
Czech Republic | |
| Řanda |
| Blumrich (1893) |
| Ulrych |
| Ulrych et al. (1998) |
| Pazdernik (1997) |
Denmark | |
| Pedersen et al. (1975) +1 other reference | |
DR Congo | |
| Richard +9 other references |
Egypt | |
| Atef et al. (2023) |
| Atef et al. (2023) | |
Eritrea | |
| Journal of Petrology |
Ethiopia | |
| Fino. M.De et al. (Ethiopia and T.F.A.I.) +1 other reference |
| Comucci (1950) +1 other reference |
| Di Paola (between 7º00' and 8º40' lat.north) +3 other references |
| Di Paola (between 7º00' and 8º40' lat.north) +3 other references | |
| Mohr (1966) +2 other references |
| Mohr (1966) +2 other references | |
| Gibson +6 other references | |
| Mohr (1962) +1 other reference | |
| Varet (1969) |
| Pagliani (1940) |
Federated States of Micronesia | |
| the evolution of a young hot spot trace across old Pacific Ocean crust. Contributions to Mineralogy and Petrology (1) +2 other references | |
France | |
| J. Aubouin |
| Brousse R (1966) | |
| Blanc Y et al. (1973) |
| Y. Blanc et al. (Haute-Loire, France) |
| Brousse +15 other references | |
| Brousse +4 other references |
| Bailey +15 other references |
| G. Demarcq |
| Eur. J. Mineral. |
| Lacroix A. (1931) +8 other references |
| Blanchard et al. (1981) +2 other references |
| Chevallier et al. (1983) |
| Nougier (1972) +21 other references | |
Germany | |
| [var: Anorthoclase-Sanidine] Engels et al. (1936) |
| Rath |
| Brauns et al. (1922) | |
| Rath |
| Rath | |
| Rath |
| Rath |
| in the collection of Christof Schäfer |
| El-Kaluoby |
| Lippolt +3 other references |
| Thomas et al. (2022) |
| Wittern (2001) |
Greece | |
| Econ Geol (1989) |
Greenland | |
| Benson (1940) |
| Parsons et al. (1981) |
| Larsen (1982) |
| Larsen (1982) | |
Honduras | |
| ... |
Hungary | |
| Vincze-Szeberényi (1982) |
| |
| |
Iceland | |
| Jørgensen (1980) +1 other reference |
| Martin et al. (2007) +1 other reference |
Iran | |
| Alberti et al. (1976) |
| Milton (1977) |
Italy | |
| Russo (2008) |
| Stoppa +13 other references |
| Gillot +13 other references |
| Joan Rosell. RosellMinerals (2021) |
| Rivista Mineralogica Italiana (1) |
| Araña et al. (1974) |
| Lustrino et al. (1996) +4 other references |
| Rossi et al. (1996) +4 other references |
| Tonarini et al. (1996) +8 other references | |
| Chester +9 other references |
| Alletti et al. (2005) |
| [Foerstner] Förstner H. (1877) +18 other references |
| [Foerstner] Förstner H. (1877) +1 other reference | |
| Rotolo et al. (2006) |
| Oretti et al. (1987) |
| Mariani P. |
| Boscardin M. et al. (2011) |
| Boscardin et al. (2011) +1 other reference |
| Boscardin M. et al. (2011) |
| Ogniben (1962) +7 other references |
Japan | |
| Yagi (1969) |
| Nemoto (1934) +1 other reference |
| |
| R. Nakanishi specimens |
| YAMAGUCHI (1964) +1 other reference |
| Yamada (2004) |
| YAMAGUCHI (1964) +1 other reference |
| Tiba (1966) |
| Gordon A. MacDonald (1948) |
| Gordon A. MacDonald (1948) | |
| PXRD by John Attard |
| Betts (n.d.) |
| Kushiro (1964) |
Kazakhstan | |
| |
Kenya | |
| Bowen N L (1935) |
| Johnshon (1969) +6 other references | |
| Matheson (1966) +2 other references | |
| Dodson (1953) +4 other references |
| Gregory (1900) +8 other references |
| Dawson et al. (2008) | |
| Saggerson (1991) |
| Scott (1980) +4 other references |
| McCall (1967) +6 other references | |
| Shackleton (1946) +2 other references |
| Smith (1938) +4 other references |
| Key (1987) | |
| Weaver et al. (1972) +1 other reference | |
| Smith (1938) +3 other references | |
| McCall et al. (1972) +3 other references | |
Libya | |
| Flinn et al (1992) |
| Flinn et al. (1992) | |
Madagascar | |
| Lacroix (1912) +3 other references |
| Lacroix (1923) +1 other reference |
| Lacroix (1923) +2 other references |
Malaysia | |
| Grubb (1965) +2 other references |
Mauritius | |
| Ashwal et al. (2016) |
| Ashwal et al. (2016) | |
Mexico | |
| Megaw |
| Biedermann et al. (2016) |
| Verhagen et al. (2023) |
Mozambique | |
| Instituto Nacional de Geologia +3 other references |
Nepal | |
| Lasserre et al. (1977) +2 other references |
New Zealand | |
| Ewart et al. (1968) +4 other references |
| NZJGG | |
| NZJGG | |
| NZJGG | |
| Sewell +7 other references |
| Speight (1907) |
| Lauder (1962) |
| Hay et al. (1970) +4 other references | |
| Smith +5 other references |
| Turner et al. (1960) +3 other references |
| Benson (1942) +1 other reference | |
| Mason (1968) +1 other reference |
| A. Reay (2002) |
| BENSON +1 other reference | |
North Korea | |
| Shinichi Kato collection |
Northwest Africa Meteorites | |
| www.sciencemag.org (2013) | |
| www.lpi.usra.edu (2015) +5 other references | |
Norway | |
| Imsland et al. (1977) +4 other references | |
| ... |
| Brögger (1894) |
| Oberti et al. (2014) |
| Eldjarn (1983) | |
Papua New Guinea | |
| Smith (1976) +1 other reference |
Peru | |
| Eur. J. Mineral. |
Poland | |
| Lis et al. (1986) |
| Lis et al. (1986) | |
| Panasiuk +4 other references |
| W. Szeliga |
| Lis et al. (1986) |
| Grabarczyk et al. (2022) |
Portugal | |
| Zanon et al. (2013) |
| Weston (1964) +4 other references |
| Samples collected by Luigi Chiappino ... +1 other reference |
| www.minersoc.org (n.d.) |
Romania | |
| Kräutner (1969) +2 other references |
Russia | |
| Rasskazov et al. (2007) |
| Shchipalkina et al. (2020) |
| Shchipalkina et al. (2020) | |
| Shchipalkina et al. (2020) | |
| alkcarb.myrocks.info (n.d.) |
| Goryachev et al. (2008) |
| Ivanyuk et al. (2007) +1 other reference |
| Arzamastsev et al. (2008) | |
| Pekov et al. (2014) +1 other reference | |
| Kapustin et al. (1975) +1 other reference |
| Menshikov et al. (2015) | |
| Menshikov et al. (2015) | |
| Konopleva et al. (2008) +1 other reference | |
| Konopleva et al. (2008) +1 other reference | |
| ... | |
| Pavel.M. Kartashov (n.d.) |
| Pavel M. Kartashov analytical data of ... | |
| Ivanyuk et al. (2012) | |
| Arzamastseva et al. (1999) +1 other reference | |
| ... |
| [World of Stones 12:49] | |
| Trunilina et al. (2022) |
Rwanda | |
| Bertossa (1968) +1 other reference |
Saint Helena， Ascension and Tristan da Cunha | |
| Baker et al. (1964) +5 other references |
Saudi Arabia | |
| shield area of western Saudi Arabia (No. 560-A) +2 other references |
| du Bray +1 other reference |
| McGUIRE (1988) +2 other references |
| Baker et al. (1973) +1 other reference |
| Liddicoat et al. (1986) |
Slovakia | |
| M. Huraiova et al. |
| Koděra (1986) |
South Africa | |
| Cairncross et al. (1995) |
South Korea | |
| Lee (1982) | |
| Atsuo Harumoto (1970) |
Spain | |
| B. Azambre et al. +1 other reference |
| Arevalo et al. (2) |
| V.R. Troll et al. | |
| Rodríguez-Losada et al. (1998) |
| Calvo (2018) |
Sweden | |
| Törnebohm (1906) +3 other references |
| Printzlau et al. (1972) +7 other references |
| Kresten (1990) |
Tanzania | |
| Stern (1969) +1 other reference |
Thailand | |
| Part II +2 other references |
Tunisia | |
| S Tunisia +1 other reference | |
Turkey | |
| Pearce et al. (1990) +9 other references |
| Cahit et al. (2000) |
| Innocenti et al. (1972) |
UK | |
| Eastwood et al. (1968) +1 other reference |
| Eastwood et al. (1968) +1 other reference | |
| Tindle (2008) | |
| B.G.J. Upton et al. |
| J. C. Phillips et al. (2013) |
| H. Downes et al. Lithos 58 2001 ... |
| |
USA | |
| Anthony et al. (1995) |
| Garcia et al. (1980) +1 other reference |
| Garcia et al. (1980) +1 other reference | |
| Caporuscio (1980) +1 other reference | |
| Evidence from xenoliths et al. (1) +1 other reference |
| WITTKE et al. (1996) |
| Erickson +1 other reference |
| Howard (1987) +1 other reference | |
| Eckel et al. (1997) |
| Carnein et al. (2005) |
| Garcia et al. (1986) +5 other references |
| Sinton (2006) |
| King et al. (1994) |
| Gilman |
| Dennen |
| Gleba (2008) | |
| Emerson |
| - (2005) |
| - (2005) |
| - (2005) | |
| - (2005) | |
| Simms (1965) |
| Castor et al. (2004) |
| Castor et al. (2004) |
| Castor et al. (2004) |
| Castor et al. (2004) | |
| MacDonald et al. (2019) | |
| Castor et al. (2004) |
| Castor et al. (2004) |
| Manchester (1931) |
| Frondel (1972) +1 other reference |
| Northrop et al. (1996) |
| Northrop et al. (1996) |
| Northrop et al. (1996) |
| Tommy B. Thompson (1973) |
| Northrop et al. (1996) |
| USGS GEOLOGIC INVESTIGATIONS SERIES ... |
| Philip M. Brown |
| Philip M. Brown | |
| Stoddard et al. (1992) | |
| Morgan VI et al. (2011) |
| Price et al. (1996) |
| J.D. Price et al. |
| - (2005) |
| Lapham & Geyer |
| Roberts et al. (1965) |
| Roberts et al. (1965) |
| Roberts et al. (1965) | |
| Smith (1991) |
| www.meteoritestudies.com (n.d.) |
| In the collection of Alex Earl |
| Bullock (1981) |
| Rocks & Min. Vol. 71 (1996) |
| Rocks & Minerals 84:352-362. |
| Dietrich (1990) | |
| Hawley (1934) |
| Cordua (1998) |
| Cordua (1998) |
| Buchholz et al. (2012) | |
| 55TH INSTITUTE ON LAKE SUPERIOR GEOLOGY (2009) |
| Robinson 1956 +1 other reference |
Yemen | |
| Cox et al. (1969) +2 other references |
| Zolensky et al. (2003) |
| Gass et al. (1968) +1 other reference |
Zimbabwe | |
| Meck et al. (2011) |
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Pili Mine, Saucillo Municipality, Chihuahua, Mexico