'Flint' in the Bible

Then Zipporah took a flint knife and cut off the foreskin of her son and threw it at Moses’ feet, and said, “Indeed you are a husband of blood to me!”

At that time the Lord said to Joshua, “Make for yourself flint knives and circumcise the [new generation of the] sons of Israel as [was done] before.”

So Joshua made flint knives and circumcised the sons of Israel at Gibeath-haaraloth.

Who turned the rock into a pool of water,The flint into a fountain of water.

Their arrows are sharp and all their bows are strung and bent;Their horses’ hoofs seem like flint and their chariot wheels like a whirlwind.

For the Lord God helps Me,Therefore, I have not been ashamed or humiliated.Therefore, I have made My face like flint,And I know that I shall not be put to shame.

I have made your forehead like emery (diamond), harder than flint. Do not be afraid of them or be dismayed before them, though they are a rebellious house.”