ES2 Metamorphic Rocks - Metamorphic Microstructures #2
Granoblastic-polygonal texture.
In this cordierite-rich granulite-facies rock, textural equilibrium is closely approached, and in section the rock consists of straight-sided polygonal cordierite grains with 120 triple junctions. Notice the very narrow biotite flake at lower right, whose basal plane the cordierite boundaries meet at right angles.

Crossed polars. Field of view is 3.5 mm across.

Sapphirine-cordierite gneiss, Namaqualand, South Africa, Sample DWN-133

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DJW - August 1997