An igneous rock with a mixed texture consisting of coarse crystals (phenocrysts)surrounded by fine crystals (groundmass)is termed
A) porphyritic.
B) phaneritic.
C) aphanitic.
D) vitric.

Question

Quizplus · Accepted Answer

The description of the rock with both coarse crystals (phenocrysts) and fine crystals (groundmass) matches the definition of a porphyritic texture. Porphyritic texture is commonly seen in volcanic rocks where large crystals form in the slower cooling chambers of the volcano (phenocrysts) and then are surrounded by rapidly cooled fine crystals (groundmass). Phaneritic texture refers to rocks that are composed of large, easily visible crystals, while aphanitic rocks have a fine-grained texture too small to see with the naked eye. Vitric rocks are characterized by a glassy texture, implying that they cooled and solidified too quickly for mineral crystals to form.

An Igneous Rock with a Mixed Texture Consisting of Coarse