A scientist identifies a rock sample as very rare. Why did he do so?
A) He observed that the rock is fine grained and has a lot of silica, making it mafic.
B) He observed that the sample is fine grained and has very little silica, making it ultra-mafic.
C) He observed that the rock is coarse grained and has a lot of silica, making it ultra-mafic.
D) He observed that the rock is fine grained and has very little silica, making it felsic.

Question

Quizplus · Accepted Answer

Ultra-mafic rocks are indeed rare and are characterized by being fine-grained with very little silica content.

A Scientist Identifies a Rock Sample as Very Rare