This mineral is called bieberite, and it is very rare in the world of mineralogy.

This rock is made of alunite.

This beautiful serpentine necklace is a gift from my mother.

This beautiful malachite necklace is my favorite.

This beautiful prehnite is part of my mineral collection.

This stone building is an ancient ruin.

This contract includes a clause of exemption from responsibility.

I was moved by his sincerity.

What is the cross-sectional area of this pillar?

In math class, we learned about finding the area of a circle.