Flint

But Zipporah took a flint knife, cut off her son’s foreskin, and touched it to Moses’ feet. “Surely you are a bridegroom of blood to me,” she said.

He led you through the vast and terrifying wilderness with its venomous snakes and scorpions, a thirsty and waterless land. He brought you water from the rock of flint.

At that time the LORD said to Joshua, “Make flint knives and circumcise the sons of Israel once again.”

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

The miner strikes the flint; he overturns mountains at their base.

…who turned the rock into a pool, the flint into a fountain of water!

Their arrows are sharpened, and all their bows are strung. The hooves of their horses are like flint; their chariot wheels are like a whirlwind.

Because the Lord GOD helps Me, I have not been disgraced; therefore I have set My face like flint, and I know that I will not be put to shame.

I will make your forehead like a diamond, harder than flint. Do not be afraid of them or dismayed at their presence, even though they are a rebellious house.”

They made their hearts like flint and would not listen to the law or to the words that the LORD of Hosts had sent by His Spirit through the earlier prophets. Therefore great anger came from the LORD of Hosts.