Asked by Jessica Lopez on Jun 11, 2024
Verified
Which of the following igneous rocks has a texture consistent with a magma that cooled and solidified slowly at first, followed by more rapid cooling?
A) small felsic crystals enclosed in large mafic ones
B) small mafic crystals enclosed in large felsic ones
C) large crystals like those in pegmatite
D) large, early formed crystals surrounded by smaller, late formed crystals
Felsic Crystals
Refers to light-colored minerals rich in elements such as aluminum, potassium, silicon, and sodium, commonly found in continental crust rocks.
Mafic Crystals
Minerals rich in magnesium and iron that crystallize from basaltic magmas, typically dark in color.
Pegmatite
An igneous rock with extremely large crystals, formed by the slow cooling of magma, often containing rare minerals.
- Gain insight into the constituents that influence the texture of igneous rocks, particularly focusing on the cooling rates.
Verified Answer
MD
Madison DieffenwierthJun 16, 2024
Final Answer :
D
Explanation :
This describes a porphyritic texture, where large crystals (phenocrysts) form in a slow-cooling environment, followed by rapid cooling that forms smaller crystals around the larger ones.
Learning Objectives
- Gain insight into the constituents that influence the texture of igneous rocks, particularly focusing on the cooling rates.