TOUCHSTONE

Calcium makes up about 1.5% of body weight. Most is stored in bones and teeth, supporting structures, nerves, and muscles. Deficiency causes osteoporosis. It occurs in limestone and calcite. Used industrially in cement, construction materials, and glass.

Chromium makes up less than 0.01% of body weight. It supports insulin activity and helps regulate blood sugar, though deficiency is rare. Geologically it occurs in chromite and is mined mainly in South Africa and Kazakhstan. Its major uses are in stainless steel, plating, and pigments.

Copper makes up about 0.0001% of body weight. It is vital for enzymes that control energy, connective tissue, iron metabolism, and antioxidants. Deficiency may cause anemia and neurological problems. Geologically, copper comes from chalcopyrite and porphyry deposits, especially in Chile and Peru. It is used in wiring, construction, and renewable energy systems.

Fluoride makes up about 0.003% of body weight. It strengthens teeth and bones. Deficiency increases the risk of cavities, while excess consumption causes fluorosis. It is found in fluorite and groundwater. Used in water fluoridation and dental care.

Iodine makes up about 0.000016% of body weight. Most is stored in the thyroid, where it is needed for hormones that regulate metabolism and development. Deficiency can cause goiter and cognitive impairment. It cycles between oceans, air, and land. Human uses include iodized salt, antiseptics, and medical imaging.

Iron makes up about 0.006% of body weight. Most is in hemoglobin for oxygen transport. Deficiency leads to anemia. Iron is mined from hematite and magnetite. It is used in the steel, machinery, and construction industries.

Magnesium makes up about 0.05% of body weight. About 25 g are stored in bones and muscles. It supports over 300 enzymes, including those involved in energy, nerve, and muscle function. Deficiency causes cramps and fatigue. It is extracted from dolomite and magnesite. Uses include alloys, fertilizers, and electronics.

Manganese makes up about 0.00012% of body weight. It is essential for bone metabolism and the function of antioxidant enzymes. Deficiency is rare but excess can damage the nervous system. It cycles through soils, rocks, and water. Manganese is extracted from pyrolusite and rhodochrosite. Industrial uses include steel, batteries, and pigments.

Molybdenum makes up about 0.00001% of body weight. It serves as a cofactor for enzymes that process sulfur compounds, purines, and toxins. In ecosystems, it supports nitrogen fixation in soils and oceans. Geologically, it occurs in molybdenite, mined in the U.S., Chile, and China. Industrial uses include steel alloys, catalysts, and aerospace materials.

Phosphorus makes up about 1% of body weight. Most is in bones and teeth, but it is also vital for DNA, ATP, and energy metabolism. Deficiency weakens bones. It comes from phosphate rock. Major uses include fertilizers, detergents, and food additives.

Potassium makes up about 0.2% of body weight. It is a key electrolyte for nerve signals, muscle contractions, heart function, and fluid balance. Deficiency can cause weakness and arrhythmias. It cycles through soils and plants, making it essential for agriculture. It is extracted from sylvite and langbeinite, primarily for use in fertilizers.

Sodium makes up about 0.1% and chloride about 0.15% of body weight. They regulate fluid balance, nerve impulses, and muscle contraction. Deficiency causes hyponatremia, excess raises hypertension risk. They are abundant in seawater and halite. Applications include food, glass, soap, and textiles.

Selenium makes up about 0.00002% of body weight. It supports the function of antioxidants and thyroid hormones. Deficiency weakens the immune system; excess is toxic. It is obtained as a byproduct of copper refining. Uses include supplements, electronics, and glass production.

Sulfur makes up about 0.25% of body weight. It is essential for amino acids, proteins, and detoxification. In Earth systems it cycles between the atmosphere, oceans, soils, and rocks, and is strongly influenced by volcanic activity and human industry. Sulfur is found in sulfide minerals and is widely used in fertilizers, chemicals, and fuels.

Zinc makes up about 0.003% of body weight. It is present in enzymes, skin, and tissues, supporting immunity, healing, and growth. Deficiency affects immunity; excess disrupts copper balance. It is sourced from sphalerite. Used in galvanizing, alloys, batteries, and agriculture.