Zinc is a chemical element1. Its official symbol is Zn, and its atomic number2 is 30, which means each zinc atom3 has 30 protons in its nucleus. Zinc is not found in its elemental form. Instead, it is found in minerals with other chemical elements. For example, sphalerite is a mineral4 that is made of zinc, iron5 and sulfur. Sphalerite ore6 is mined in Australia and many other countries. Roasting (heating) the sphalerite separates zinc from the other components.
We use a lot of zinc – it is the fourth most widely used metal7 after iron, aluminium and copper8. In 2017, worldwide use was over 14 million metric tons.
Elemental history
For 2,500 years, humans have mixed zinc with copper to make brass, an alloy9. The ancient Romans and others in Middle Eastern regions used brass to make coins and ornamental items. The zinc they used was impure (mixed with other substances). It wasn’t until 800 years ago that experts in India discovered how to smelt10 minerals and ores to create metallic zinc.
Even though India recognised zinc as a metal in 1374 and an English metallurgist had patented a process to distil zinc in 1738, it was ‘officially discovered’ in 1746 by German chemist11 Andreas Marggraf. Marggraf received credit for the discovery because he published the distillation process in careful detail.
Industrial uses of zinc
Zinc is still used in the production of brass and bronze, just like it was thousands of years ago. A more modern use is in electrical batteries. Alkaline12 batteries have zinc powder inside them.
More than half of the zinc used today is to galvanise (coat) other metals like iron and steel. The protective zinc coating slows the metals from rusting13 or corroding14. If you look closely at metal poles used in a chain-link fence or an outdoor handrail, you can see the protective coating.
Zinc compounds
Zinc compounds have a variety of uses. Zinc chloride is often added to timber as a chemical fire retardant. Zinc sulfide is used in fluorescent bulbs – it converts ultraviolet light to visible light.
Zinc oxide15 is used as a white pigment16 in paint. (If you have a set of oil paints, check to see if your tube of white paint has the word zinc in its name.)
Zinc oxide is used in sunscreen17. It forms a barrier on the skin and reflects or scatters the UV waves. People who spend a lot of time in the sun – cricket players for example – may use a thick, white zinc cream on their nose or lips.
Most sunscreens look white at first but become clear when rubbed on the skin because the zinc oxide consists of tiny nanoparticles. There was concern that these nanoparticles might be dangerous, but a 2018 study showed that the tiny particles do not penetrate the skin or harm skin cells.
On the farm, zinc oxide drenches are used to prevent or treat facial eczema18 in sheep and cattle. It is a disease19 that damages the animal’s liver20. The animals can also receive zinc in a pill form or in their drinking water.
Nature of science
Not all science is done in the lab. In the 1940s, Gladys Reid – a farmer, dental nurse and citizen scientist living in Te Aroha – discovered that putting zinc salts in water troughs was the best prevention for facial eczema21 in livestock. Gladys recognised the importance of evidence22 and used control23 groups to test her ideas. Gladys’s remedy is still in use today!
Zinc and health
Zinc is an essential trace element for most forms of life. Human adults, on average, have 2–4 grams of zinc in their bodies. Most people get enough zinc from the foods they eat – meat, shellfish, eggs, legumes24, pumpkin and sesame seeds, cashew nuts, potatoes and dairy products are good sources of zinc. Our bodies do not store zinc, so it is important to eat a wide variety of foods every day to replace it.
Zinc plays an important role in our immune systems and helps to heal wounds. There is evidence that zinc can help with the common cold if used within 24 hours of the symptoms appearing. Experts say more research is needed to determine the dose25.
Not having enough zinc in our bodies can slow growth, interfere with our ability to reproduce, lower our immunity26 and interfere with our sense of smell.
Related content
The Parliamentary Commissioner for the Environment report Knowing what’s out there: Regulating the environmental fate of chemicals includes a case study of how zinc-based substances are used, regulated27 and monitored in New Zealand.
Useful links
Read the news release from EurekAlert Realistic exposure study supports the use of zinc oxide nanoparticle sunscreens.
DairyNZ has information about facial eczema:
Read about citizen scientist Gladys Reid and her efforts to prevent facial eczema.
The National Institutes of Health website has a zinc health information fact sheet.
LiveScience Facts about zinc has information about the role of zinc in human reproduction.
- element: A substance made of atoms that all have the same atomic number. Elements cannot be split into simpler substances using normal chemical methods.
- atomic number: The number of protons in the nucleus of an atom. This determines an element’s properties and location on the periodic table of elements.
- atom: The smallest possible unit of matter that still maintains an element’s identity during chemical reactions. Atoms contain one or more protons and neutrons (except hydrogen (H), which normally contains no neutrons) in a nucleus around which one or more electrons move.
- mineral: 1. (Geology) A naturally occurring solid formed through geological processes. Any given mineral has a characteristic chemical composition and a specific set of physical properties. 2. (Dietary) An inorganic compound needed for proper body function and maintenance of health, for example, iron in the form of haeme present in red meat.
- iron: A chemical element with the symbol Fe.
- ore: Rock or sediment from which we can extract elements and minerals.
- metal: Any of a category of elements that usually have a shiny surface, are generally good conductors of heat and electricity and can be melted or fused, hammered into thin sheets or drawn into wires (for example, copper).
- copper: A transition metal in Group 11 of the periodic table – symbol Cu, atomic number 29.
- alloy: A mixture of a metal with one or more other elements to modify its metallic properties, for example, brass is an alloy of copper and zinc.
- smelt: To get metal from rock by heating it to a very high temperature. To melt objects made from metal in order to reuse the metal.
- chemist: A scientist trained in the science of chemistry. Chemists study the composition of matter and its properties.
- alkaline: A solution that has a pH value greater than 7.
- rust: An orange-red coating that forms on metals containing iron when exposed to air and moisture.
- corrode: The gradual wearing away of a substance, usually caused by a chemical reaction. One example of corrosion is rust forming on iron.
- oxide: A chemical compound made up of oxygen combined with at least one other element. Most of the Earth’s crust consists of oxides.
- pigment: Any fine, insoluble, dry, solid particles used to give colour. In biology, the dye-like material produced generally in the superficial parts of animals that gives colour to skin, eyes and hair.
- sunscreen: A product applied to the skin to protect it from the effects of the Sun's rays. Sunscreens act by absorbing or reflecting ultraviolet radiation.
- facial eczema: A disease affecting mainly cattle, sheep, deer and goats. It is caused by sporidesmin – a toxin that produces liver damage. Sporidesmin is produced on pasture plants, including rye grass, by the fungus Pithomyces chartarum.
- diseases: 1. An abnormal condition of an organism that impairs bodily functions. 2. In plants, an abnormal condition that interferes with vital physiological processes.
- liver: A vital organ situated beside the stomach. It is the body’s largest internal organ and plays a major role in metabolism as well as other important and complex functions.
- eczema: An inflammation of the skin making it red and sometimes dry, flaky or itchy.
- evidence: Data, or information, used to prove or disprove something.
- control: 1. Part of a scientific experiment in which no treatment has been applied in order to see whether there are any detectable differences to the experiment that did receive a treatment. 2. To hold in check or to curb.
- legume: A plant having fruits that are developed from a simple superior ovary and usually dehiscing into two valves. Legumes bear nodules on the roots, which contain nitrogen-fixing bacteria. Examples are peas, beans and clovers.
- dose: The amount of a substance that comes into contact with a living organism or some part of a living organism.
- immunity: A body's reaction to the introduction of foreign substances, through the production of defensive substances such as antibodies.
- regulated: Controlled by rules and laws. In biology: To adjust a bodily function or process. In genetics: To control the expression of a gene or genes.
