How would you correctly refer to the metamorphic grade of a rock that contains bundles of fibrous sillimanite along with pyroxene and sanidine as its highest temperature minerals such as a coarse grained granulite facies gneiss? A) high grade 600° C B) intermediate grade C) "S grade" D) low grade

Question

How would you correctly refer to the metamorphic grade of a rock that contains bundles of fibrous sillimanite along with pyroxene and sanidine as its highest temperature minerals such as a coarse grained granulite facies gneiss?
A) high grade > 600° C
B) intermediate grade
C) "S grade"
D) low grade < 200° C

Quizplus · Accepted Answer

The presence of fibrous sillimanite along with pyroxene and sanidine in a coarse-grained granulite facies gneiss indicates a high-grade metamorphic rock, which typically forms at temperatures greater than 600° C.

How Would You Correctly Refer to the Metamorphic Grade of a Rock