Phengite
Phengite is a series name for dioctahedral micas of composition K(Al,Mg)2(OH)2(Si,Al)4O10. It is common for Mg or Fe2+ to substitute for Al on the Y site and a corresponding increase in Si on the Z site in the mica group formula X2Y4–6Z8O20(OH, F)4. Similar to muscovite but with addition of magnesium. It is a non-IMA recognized mineral name representing the series between muscovite and celadonite.
| Phengite | |
|---|---|
| General | |
| Category | Mica group |
| Formula (repeating unit) | K(AlMg)2(OH)2(SiAl)4O10 |
The silica content of phengite has been proposed as a geobarometer for the metamorphism of low grade schists.
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.