The teeth are the hardest substances in the human body.

It seems to me that I merely ran into some hard substance which barred my way.

The piece of iron looked as if it had been crushed between two very hard substances.

We're offering cold, hard substance and you want us to bake them a cake!

It was the hardest substance I've ever worked with, because it's disgusting.

It is the hardest substance found native, next to the diamond.

The enamel on teeth is the hardest substance in the human body.

He caught a metallic note; the leaves might be some hard substance.

He brought it flaming down on the hard, rocky substance of the city square.

Where was the hard substance of this matter to be found?