Metamorphic Grade III - Mineral Sequences

The following Mineral changes are used to recognize increasing grade - they are marked by the first appearance of the new mineral not the last of the old.

Muscovite -> Andalusite -> Kyanite -> Sillimanite
Chlorite -> Biotite -> garnet(Almandite)
Chlorite -> Biotite -> Hornblende -> Pyroxene
Calcite -> Epidote -> Plagioclase

These can be grouped into a series of Pressure-Temperature zones or a sequence of mineral facies(groups).

Facies:
Zones:
Greenschist 
Epidote-Amphibolite 
Garnet-Amphibolite 

Amphibolite
Chlorite
Biotite 
Garnet 
Staurolite 
Kyanite 
Sillimanite

 
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Copyright William C. Wilson 1997
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Website created: January 22, 1998
Website last updated: November 18, 2000