Mantled porphyroclast

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[Object/Geometry]-----Porphyroclast with an elongatedmantle of the same mineral composition, stretched inthe direction of the foliation. It is inferred to have formedat the expense of the porphyroclast by recrystallisationin its rim. Mantled porphyroclasts are common in mylonitesand are used to determine sense of shear. See alsoδ-type object, σ-type object and strain shadow. (Passchier and Trouw, 2005)