Calamine (mineral)

Calamine is a historic name used for ores containing zinc.

While the term is no longer used in formal mineralogy, it has a long history in industry. The name itself comes from the Latin term lapis calaminaris. This was a version of the Greek word cadmia, which was an old name for zinc ores. The name is even reflected in the Belgian town of Kelmis, known in French as La Calamine. This town was once home to a zinc mine. For centuries, people relied on these ores to produce essential metals and alloys.

In the early history of metallurgy, calamine was vital for making brass.

In 16th-century England, there was a high demand for a metal called latten, which is a type of brass. This metal was needed for brass-wire combs used in wool-carding. It was also used for battery pieces, which are items made by hammering sheet brass in a mill. To create this alloy, workers used the cementation process. This involved heating copper and calamine together to combine them. In 1568, a royal charter was granted to the Society of the Mineral and Battery Works. This group searched for minerals to reduce England's dependence on German imports.

As technology changed, the way people worked with zinc evolved. By the late 17th century, people understood metallic zinc well enough to make brass solder. They did this by combining copper with spelter, which are zinc ingots. A major breakthrough occurred in 1738 for the brass industry. A Bristol brass founder named William Champion was granted a patent. His patent allowed for the large-scale reduction of calamine to produce spelter. Near his works in Shipham, many calamine mines provided the necessary materials for this industrial process.

For a long time, scientists believed calamine was a single mineral. However, researchers discovered that it actually consisted of two distinct minerals.

The first is smithsonite, which is a zinc carbonate (ZnCO3). The second is hemimorphite, which is a zinc silicate (Zn4Si2O7(OH)2·H2O). These two minerals are chemically and crystallographically different. Despite these differences, they look very similar to the naked eye. They often share a massive or botryoidal external form. Botryoidal means the mineral has a shape that looks like a cluster of grapes.

Because they look so much alike, they are hard to tell apart without analysis. The British chemist and mineralogist James Smithson solved this mystery. In 1803, he became the first person to separate the two minerals. Because of his work, the term calamine is no longer considered valid in mineralogy. Using the specific names smithsonite and hemimorphite prevents confusion. It also helps distinguish these ores from calamine lotion. That lotion is a pinkish mixture of zinc oxide (ZnO) and iron(III) oxide (Fe2O3).

Throughout history, many important mining sites have been found. Large ore mines were located near the German village of Breinigerberg during the 18th and 19th centuries. Other significant specimens have been found in places like Granby, Missouri, and the Sterling Hill mine in New Jersey.

These locations provided the raw materials that drove the development of metalworking and chemistry. The study of these minerals helped move science from simple metalworking toward modern mineralogy.

Beyond metal, calamine has also been used in medicine. In 1684, a paper presented to the Royal Society discussed its medicinal and veterinary uses. This was in the form of a finely powdered compound. While scientists have not identified a specific mechanism of action, they observed a physical effect. The powder has the ability to absorb moisture from irritated or weeping skin. This simple physical property has kept the name "calamine" alive in a different context, even as the mineral name has changed.