ES2 Metamorphic Rocks - Metamorphic Microstructures #3
Decussate texture.
This rock represents a good approach to textural equilibrium in a rock composed almost entirely of muscovite. Because muscovite has a strong tendency to form tabular crystals with well-developed basal {001} faces, the texture is not granoblastic-polygonal, but consists of randomly-oriented interlocking flakes. The low interference colours are shown by grains whose basal section is close to the plane of the thin section.

Crossed polars. Field of view is 1.5 mm across.

Muscovite rock, Lewisian gneiss complex, Stoer, NW Scotland, Sample DWS-161

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DJW - August 1997