| 41. | The Twin Lakes lava is black, porphyritic and has abundant xenocrysts of quartz ( see Cinder Cone ).
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| 42. | The rock has a porphyritic texture with large crystals of orthopyroxene and phlogopite set in a fine grained matrix.
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| 43. | To the west are a few mafic porphyritic basalts and possibly older Miocene basalts cut by dykes and faults.
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| 44. | In this connection we may repeat what has been said above about the corrosion of porphyritic minerals in igneous rocks.
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| 45. | Many examples are banded or striated; others contain porphyritic crystals of quartz which resemble those of the felsites and porphyries.
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| 46. | The leucite is often present in two sets of crystals, both porphyritic and as an ingredient of the ground mass.
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| 47. | The "'Palisades Sill "'is a fine-grained porphyritic dacite Cimarron in northern New Mexico.
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| 48. | This can be roughly translated to'Red River', perhaps reflecting the red porphyritic pebbles found here in large numbers.
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| 49. | The Paleozoic strata have been intruded by numerous dikes, and sheets of basalts, andesite-basalts, and porphyritic diorite.
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| 50. | The primary benefit of calculating a CIPW norm is determining what the ideal mineralogy of an aphanitic or porphyritic igneous rock is.
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