Minerals identify

Know how to recognize them


Mica group

Phengite is a series name for dioctahedral micas of composition K(AlMg)2(OH)2(SiAl)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 X2Y4–6Z8O)4. Similar to muscovite. It is a non-IMA recognized mineral name representing the series between muscovite and celadonite

The silica content of phengite has been proposed as a geobarometer of low grade schists