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A. Ragged subhedral phenocryst of hornblende in a sample of porphyry. It has been partly replaced by fibrous amphibole. Where intact, the hornblende displays two directions of cleavage. Also shown are a diamond-shaped phenocryst of sphene, two small bits of hornblende (lower right), and small crystals of magnetite at two locations. The field of view is about 0.8 x 1.2 mm. Plane-polar light. DDH 464-9.
