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anorthosite
Sign in to saveAnorthosite () is a phaneritic, intrusive igneous rock characterized by its composition: mostly plagioclase feldspar (90–100%), with a minimal mafic component (0–10%). Pyroxene, ilmenite, magnetite, and olivine are the mafic minerals most commonly present.
Key facts
- Rock.type
- Igneous
- Rock.name
- Anorthosite
- Rock.type_link
- igneous rock
- Rock.image
- Anorthosit of Salem Tamil Nadu.jpg
- Rock.image_size
- 200
- Rock.caption
- Anorthosite from Salem district, Tamil Nadu, India
- Rock.composition
- Plagioclase
- Rock.composition_secondary
- Mafic minerals
via Wikipedia infobox
Article
17 sectionsContents
- Proterozoic anorthosite massifs
- Age
- Occurrence
- Related rocks
- Physical characteristics
- Chemical and isotopic characteristics
- High-alumina orthopyroxene megacrysts (HAOMs)
- Origins of Proterozoic anorthosites
- Lunar anorthosite
- Archean anorthosites
- Economic value
- Contents
- Soil development on anorthosite
- See also
- References
- Bibliography
- External links
Anorthosite () is a phaneritic, intrusive igneous rock characterized by its composition: mostly plagioclase feldspar (90–100%), with a minimal mafic component (0–10%). Pyroxene, ilmenite, magnetite, and olivine are the mafic minerals most commonly present.
Anorthosites are of enormous geologic interest, because it is still not fully understood how they form. Most models involve separating plagioclase crystals based on their density. Plagioclase crystals are usually less dense than magma; so, as plagioclase crystallizes in a magma chamber, the plagioclase crystals float to the top, concentrating there.