Oil is an important element of the world economy.

I saw a wagtail in the park.

This piece of art is made of serpentine.

This sudoite is something I inherited from my grandfather.

This necklace is made of beautiful malachite.

He is suffering from deep loneliness.

He was sitting alone in the room, feeling lonely.

This beautiful prehnite necklace is my favorite.

Mr. Sekiguchi is my best friend.

This plan is like killing two birds with one stone, it can save both time and money.