Large crystals found in a fine-grained groundmass can indicate what?
A) origin from a magma with an early intrusive phase followed by an extrusive phase
B) origin from a magma with an early extrusive phase followed by an intrusive phase
C) a rock of mixed volcanic-plutonic origin
D) intrusive slow cooling
E) origin from a magma with an early intrusive phase followed by an extrusive phase; a rock of mixed volcanic-plutonic origin

Question

Quizplus · Accepted Answer

Large crystals found in a fine-grained groundmass indicate a rock of mixed volcanic-plutonic origin, which is formed when magma initially intrudes and cools slowly to form large crystals, and then erupts to form a fine-grained groundmass.

Large Crystals Found in a Fine-Grained Groundmass Can Indicate What