Microminerals (also called trace minerals) are essential dietary minerals required by an organism in very small quantities for proper growth, development, and physiological functions. Macrominerals, on the other hand, are required in larger quantities. Iodine is a trace mineral essential for the synthesis of thyroid hormones. Magnesium, Phosphorus, and Sulphur are classified as macrominerals because they are needed in larger amounts by the human body.