Calcium is the fifth most abundant element in the earth's crust. Calcium helps build strong bones and teeth, and as a dietary supplement aids in the formation of healthy muscle tissue, aids in blood clotting, and in maintenance of cell membranes. Iron ore is probably the most important mineral civilized man has ever dug from the earth. In ancient times, it was the strongest and hardest known metal. It is typically magnetic.
Magnetite is the raw material used for the production of iron and steel.
Iron is an essential human nutrient, primarily as a carrier of oxygen in the body. It is contained in hemoglobin in the blood and myoglobin in the muscles. Dark or brassy in color, often with an iridescent film coating. Only silver is a better electrical conductor than copper. Bronze, which is made by combining copper and tin, was used by the ancient Egyptians and Romans.