Astronomers spend a lot of time studying blue giants.

He is majoring in mineralogy at university.

Mineral oil is often used in the manufacture of cosmetics and pharmaceuticals.

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

This mineral is called melanterite, and it has a vivid green color.

He underwent bile duct surgery.

He called me back immediately after he hung up the phone.

A blue supergiant is one of the brightest stars in the universe.

We are developing new technologies to mine bauxite.

He is always hanging out with bad friends. Truly, birds of a feather flock together.