Author Question: The minerals andalusite, sillimanite, and kyanite all have the chemical formula, Al2SiO5. Explain ... (Read 68 times)

armygirl · **on:** Jul 13, 2018

The minerals andalusite, sillimanite, and kyanite all have the chemical formula, Al2SiO5. Explain how three different minerals can have the same chemical components and why this fact is important.

Question 2

The age of oceanic crust in the Pacific is asymmetric because ____.
A)much of the crust in the eastern Pacific has been subducted
B)spreading is faster on the east side of the ridge than on the west side
C)the eastern Pacific collided with the Americas to form mountain ranges
D)volcanism on the west side of the ridge has made the crust larger
E)almost none of the crust in the eastern Pacific has been subducted

sultana.d · **Reply #1 on:** Jul 13, 2018

Answer to Question 1

Even thought andalusite, sillimanite, and kyanite have the same chemical formula, they differ in crystal structure and other physical properties because each forms under a different range of pressures and temperatures and is thus reflective of a different metamorphic grade. For this reason, they are useful index minerals for metamorphic rocks that formed from clay-rich rocks.

Answer to Question 2

A