ES2 Metamorphic Rocks - Metamorphic Microstructures #18
Reaction rim #1.
Detail of a complex reaction rim or corona formed between quartz (above) and greenish-blue sapphirine (below) as this granulite-facies rock cooled from very high temperature. From top to bottom, the three shells of the reaction rim are orthopyroxene, cordierite and sillimanite.

Field of view is 1 mm across.

Sapphirine gneiss, Wilson Lake, Labrador.

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DJW - August 1997