'Black' in the Bible

Nor should you swear by your head, because you cannot make one hair white or black.

When the lamb opened the third seal, I heard the third living creature say, "Go!" I looked, and there was a black horse! Its rider held a scale in his hand.

Then I saw the lamb open the sixth seal. There was a powerful earthquake. The sun turned as black as sackcloth made of hair, and the full moon turned as red as blood.