ES2 Metamorphic Rocks - Metamorphic Microstructures #14
Inclusion patterns in andalusite.
Here a porphyroblast of andalusite has grown (from bottom left) over a fine-grained matrix of quartz, mica and graphite. Certain parts of the crystal have apparently been able to advance against the matrix without enclosing matrix grains, whereas other regions have trapped abundant small inclusions. Note the black accumulations of passively-displaced graphite on the straight external faces of the andalusite.
Field of view is 4 mm across.
Andalusite hornfels, Longsight, aureole of the Bushveld Complex, South Africa. Sample BM-3.
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DJW - August 1997