Malachite: Properties, Facts and Photos

Malachite is a green copper carbonate mineral that forms near the Earth’s surface and is widely known as an important ore of copper and a decorative stone. This article explores what it is, its history, and physical properties. 

What is Malachite?

Malachite is a classic green mineral and one of the oldest ores of copper. It forms near the Earth’s surface when copper-rich groundwater circulates through fractures, cavities, and porous rocks. As the water reacts with oxygen and carbon dioxide, copper minerals are altered and redeposited as malachite, often lining cavities or forming botryoidal and fibrous masses.

An ore is a rock that contains a significant amount of a natural mineral with valuable elements that can be extracted.

The presence of malachite often indicates that deeper deposits of native copper are nearby.

Extracting copper from malachite involves heating the stone with carbon at a relatively low temperature for a short period of time. 

As a copper carbonate hydroxide mineral, malachite forms from water-based chemical processes rather than high-temperature geological activity. This explains why it commonly occurs in weathered zones above deeper copper deposits.

Malachite often occurs alongside azurite. The chemical formula for both minerals is very similar. They're produced through the weathering of copper ore deposits.

When azurite and malachite combine, the stone is known as azurite-malachite.

Malachite is green and azurite blue because the copper in malachite is more highly oxidised than in azurite. Over time and under the right conditions, azurite can turn into malachite. This transformation is known as pseudomorphism, which literally means 'false form.'

In geology, pseudomorphs are minerals that have undergone a transformation whereby one changes into another while retaining the external crystal shape of the original mineral.

Azurite can be altered to malachite through a chemical reaction that involves the addition of water and oxygen and the release of carbon dioxide. The alteration happens because azurite is less stable at or near the Earth’s surface. When exposed to water and oxygen, its structure changes, reducing the carbonate content and forming malachite.

The process of pseudomorphism can vary greatly. In one example, which is petrified wood, the original organic structure is slowly replaced by silica.

The History of Malachite

Although malachite dates back to 8000 BC, it wasn't used as an ore until 5000 BC. Until then, copper, which was the only metal known to humans, would have come from deposits of native copper.

Malachite was used as an ore of copper throughout antiquity. The ancient Egyptians had mining operations in place in the Sinai Peninsula in 4000 BC. This area was Egypt's main source of copper for thousands of years.

Many ancient civilisations used malachite for decorative purposes. It's also believed to have been the first green pigment, which led to it being used as a colouring agent in glazes, glass and cosmetics.

In China, green pigment can be traced back to the Shāng people [c.1500 BC]. A tiger carved from malachite found in the tomb of a King's consort was dated to around the same period.

In Western China, the colour green appears in paintings from the ninth and tenth centuries, but it didn't become popular in Europe until around the 14th century. In ancient Egyptian tomb paintings, the colour green first appeared around 2613 BC.

Malachite beads found on the Euphrates River date back to 7000 BC.

When used as a pigment, malachite must be coarsely ground because if the particles are too small, the colour will be much paler. 

The Pharaoh Amenhotep III used over five hundred kilos of mafek for inlay work in the Temple of Karnak. Mafek was a collective name for various green stones, one of which is believed to have been malachite.

Sorting objects into groups is an instinctive human characteristic. For thousands of years, rocks and minerals were grouped according to colour and visible properties. Records from the earliest system show two groups: stones and earths. Rocks and minerals were put into one of the two groups depending on how they reacted to fire and water.

In the writings of Theophrastus, the ancient Greek philosopher, all bright green copper minerals were labelled as chrysocolla.

More than three centuries later, the Roman author Pliny the Elder wrote extensively about a green copper substance he called chrysocolla in his encyclopaedia, Naturalis Historia. He described it as a naturally occurring green material found in copper mines, used both as a pigment and as a flux.

Although he treated chrysocolla as a distinct substance, modern mineral historians believe the term was used loosely for a range of green copper minerals and may often have referred to malachite rather than the mineral known today as chrysocolla.

If true, this means the mineral known today as chrysocolla may not have been known.

In the same work, Pliny also refers to a group of green-coloured stones as varieties of smaragdus, yet many had little in common. Smaragdus is an ancient name for emerald.

The group to which he's referring is believed to have included malachite, types of sapphire, turquoise, jasper, and possibly even glass.

He wrote, "Copper smaragdus from Cyprus is associated with the colour blue." This seems to be a reference to the mineral azurite.

In the early 1800s, two enormous deposits of malachite were discovered in Russia, with enough stone to supply the entire country with copper for around 170 years.

Many large slabs were polished for ornamental purposes, and malachite quickly became the stone of choice for the rich and famous.

Today, several of Russia's most important buildings are adorned with malachite. One is The Malachite Room at the Winter Palace in St Petersburg, which features over 200 tons.

Saint Isaac's Cathedral in St. Petersburg was built over forty years, starting in 1818. It features marble, granite, lapis lazuli, and eight massive green malachite pillars.

More About Malachite

On the Mohs scale, malachite grades 3.5 to 4. As well as being very soft, it's also porous, so it absorbs moisture and can stain or scratch easily. Sudden exposure to heat can affect its colour or cause cracks.

Despite these challenging characteristics, malachite has always been a popular carving material. When used as a gemstone, it's cut as a cabochon.

The carbonate component of malachite makes it sensitive to acids. Even weak acidic solutions can slowly react with the surface, causing stones to lose their polish or develop etched areas over time.

The dust from malachite is highly toxic, so protective breathing equipment must be worn while stones are being cut and polished.

When used for its metaphysical properties, malachite should never be used as an elixir, which is water infused with natural minerals to extract their healing properties. The water is then consumed.

Article Pictures

The malachite in the first and fourth pictures are from our collection.

The second picture is native copper with malachite. Photo: Courtesy of Stan Celestian.

The malachite in the third picture is in the Smithsonian Museum of Natural History in Washington, D.C. Photo: Stone Mania.

The malachite vases are in the Hermitage Museum, St Petersburg.

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Native copper, azurite, chrysocolla, pseudomorph (malachite after azurite): Courtesy of Stan Celestian.