The mineral primarily responsible for the red color in blood is iron, specifically in the form of hemoglobin. Hemoglobin is a protein found in red blood cells and is crucial for transporting oxygen throughout the body. Each hemoglobin molecule contains iron atoms that bind with oxygen, allowing for the efficient distribution of oxygen from the lungs to tissues. When oxygen is bound to iron in hemoglobin, the blood appears bright red, while deoxygenated blood has a darker, bluish hue. The presence of iron is essential not only for respiration but also for overall cellular metabolism.