Log In
Anorthositoid
A rock classification type
This page is currently not sponsored. Click here to sponsor this page.
About Anorthositoid
Name:
For its constitution, anorthite-rich.
A coarse-grained crystalline normal igneous rock composed mostly of plagioclase. Anorthosite is usually an intrusive rock characterised by its composition: mostly calcian plagioclase feldspar (anorthite) (90–100%), with a small mafic component (0–10%). Pyroxene, ilmenite, magnetite and olivine are commonly present as minor components.
Unique Identifiers
Mindat ID:
50547
Long-form identifier:
mindat:1:1:50547:7
Classification of Anorthositoid
Anorthositic rocks are in sections 10,10* and 10' of the QAPF diagram.
Sub-divisions of Anorthositoid
Mineralogy of Anorthositoid
Essential minerals - these are minerals that are required within the classification of this rock:
| Feldspar > Plagioclase > Anorthite | Ca(Al2Si2O8) |
Non-essential minerals - these minerals are common, sometimes major components, but are not always present:
| Amphibole > Hornblende | AnCa2(Z2+5-mZ3+m)(Si8-(n+m)Al(n+m))(OH,F,Cl)2 |
| Mica > Biotite | K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2 |
| Olivine Group | M2SiO4 |
| Pyroxene | ADSi2O6 |
Synonyms of Anorthositoid
Internet Links for Anorthositoid
mindat.org URL:
https://www.mindat.org/min-50547.html
Please feel free to link to this page.
Please feel free to link to this page.
References for Anorthositoid
Reference List:
Alma quarry, Lac-Saint-Jean-Est RCM, Saguenay-Lac-Saint-Jean, Québec, Canada