Malachite is a copper carbonate hydroxide mineral, with the

formula In science, a formula is a concise way of expressing information symbolically, as in a mathematical formula or a ''chemical formula''. The informal use of the term ''formula'' in science refers to the general construct of a relationship betwee ...

Cu₂CO₃(OH)₂. This opaque, green-banded mineral crystallizes in the monoclinic crystal system, and most often forms botryoidal, fibrous, or

stalagmitic A stalagmite (, ; from the Greek , from , "dropping, trickling") is a type of rock formation that rises from the floor of a cave due to the accumulation of material deposited on the floor from ceiling drippings. Stalagmites are typically ...

masses, in fractures and deep, underground spaces, where the water table and hydrothermal fluids provide the means for chemical precipitation. Individual crystals are rare, but occur as slender to acicular prisms. Pseudomorphs after more tabular or blocky azurite crystals also occur.

Etymology and history

The stone's name derives (via la, molochītis, frm, melochite, and Middle English ''melochites'') from Greek Μολοχίτης λίθος ''molochites lithos'', "mallow-green stone", from μολόχη ''molochē'', variant of μαλάχη ''malāchē'', "mallow". The mineral was given this name due to its resemblance to the leaves of the mallow plant. Malachite was mined from deposits near the Isthmus of Suez and the Sinai as early as 4000 BCE. It was extensively mined at the

Great Orme Mines The Great Orme ( cy, Y Gogarth) is a limestone headland on the north coast of Wales, north-west of the town of Llandudno. Referred to as ''Cyngreawdr Fynydd'' by the 12th-century poet Gwalchmai ap Meilyr, its English name derives from the Old N ...

in Britain 3,800 years ago, using stone and bone tools. Archaeological evidence indicates that mining activity ended , with up to 1,760 tonnes of copper being produced from the mined malachite. Archaeological evidence indicates that the mineral has been mined and smelted to obtain copper at Timna Valley in Israel for more than 3,000 years. Since then, malachite has been used as both an ornamental stone and as a gemstone.

Occurrence

Malachite often results from the

supergene A supergene is a chromosomal region encompassing multiple neighboring genes that are inherited together because of close genetic linkage, i.e. much less recombination than would normally be expected. This mode of inheritance can be due to genomic ...

weathering and oxidation of

primary Primary or primaries may refer to: Arts, entertainment, and media Music Groups and labels * Primary (band), from Australia * Primary (musician), hip hop musician and record producer from South Korea * Primary Music, Israeli record label Works * ...

sulfidic copper ores, and is often found with azurite (Cu₃(CO₃)₂(OH)₂), goethite, and

calcite Calcite is a Carbonate minerals, carbonate mineral and the most stable Polymorphism (materials science), polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on ...

. Except for its vibrant green color, the properties of malachite are similar to those of azurite and aggregates of the two minerals occur frequently. Malachite is more common than azurite and is typically associated with copper deposits around limestones, the source of the carbonate. Large quantities of malachite have been mined in the Urals, Russia. Ural malachite is not being mined at present, but G.N Vertushkova reports the possible discovery of new deposits of malachite in the Urals. It is found worldwide including in the Democratic Republic of the Congo; Gabon; Zambia; Tsumeb, Namibia; Mexico;

Broken Hill, New South Wales Broken Hill is an inland mining city in the far west of outback New South Wales, Australia. It is near the border with South Australia on the crossing of the Barrier Highway (A32) and the Silver City Highway (B79), in the Barrier Range. It is ...

; Burra, South Australia; Lyon, France; Timna Valley, Israel; and the

Southwestern United States The Southwestern United States, also known as the American Southwest or simply the Southwest, is a geographic and cultural region of the United States that generally includes Arizona, New Mexico, and adjacent portions of California, Colorado, Ne ...

, most notably in Arizona.

Structure

Malachite crystallizes in the

monoclinic system In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in the orthorhombic s ...

. The structure consists of chains of alternating Cu²⁺ ions and OH⁻ ions, with a net positive charge, woven between isolated triangular CO₃²⁻ ions. Thus each copper ion is conjugated to two hydroxyl ions and two carbonate ions; each hydroxyl ion is conjugated with two copper ions; and each carbonate ion is conjugated with six copper ions. File:Malachite 001.png, View along ''c'' axis of the crystal structure of malachite File:Malachite 100.png, View along ''a'' axis of malachite crystal structure File:Malachite 010.png, View along ''b'' axis of malachite crystal structure File:Malachite-unit-cell-3D-bs-17.png, Unit cell of malachite File:Malachite-xtal-Cu1-coordination-3D-bs-N17-M25.png,

Coordination environment In coordination chemistry, the first coordination sphere refers to the array of molecules and ions (the ligands) directly attached to the central metal atom. The second coordination sphere consists of molecules and ions that attached in various ...

of copper 1 File:Malachite-xtal-Cu2-coordination-3D-bs-N17-M25.png, Coordination environment of copper 2 File:Malachite-xtal-carbonate-coordination-3D-bs-N17-M25.png, Coordination environment of carbonate File:Malachite-xtal-hydroxide-O4-coordination-3D-bs-N17-M25.png, Coordination environment of hydroxide 1 File:Malachite-xtal-hydroxide-O5-coordination-3D-bs-N17-M25.png, Coordination environment of hydroxide 2

Use

Malachite was used as a mineral pigment in green paints from antiquity until 1800. The pigment is moderately

lightfast Lightfastness is a property of a colourant such as dye or pigment that describes its resistance to fading when exposed to light. Dyes and pigments are used for example for dyeing of fabrics, plastics or other materials and manufacturing paints or ...

, sensitive to

acid In computer science, ACID ( atomicity, consistency, isolation, durability) is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. In the context of databases, a sequ ...

s, and varying in color. This natural form of green pigment has been replaced by its synthetic form, verditer, among other synthetic greens. Malachite is also used for decorative purposes, such as in the Malachite Room in the Hermitage Museum, which features a huge malachite vase, and the Malachite Room in Castillo de Chapultepec in Mexico City. Another example is the Demidov Vase, part of the former Demidov family collection, and now in the Metropolitan Museum of Art. "The Tazza", a large malachite vase, one of the largest pieces of malachite in North America and a gift from Tsar Nicholas II, stands as the focal point in the centre of the room of Linda Hall Library. In the time of Tsar Nicolas I decorative pieces with malachite were among the most popular diplomatic gifts. It was used in China as far back as the Eastern Zhou period. The base of FIFA World Cup Trophy has two layers of malachite.

Symbolism and superstitions

A 17th-century Spanish superstition held that having a child wear a lozenge of malachite would help them sleep, and keep evil spirits at bay.

Marbodus Marbodus, Marbod or Marbode of Rennes ( 1035 – 11 September 1123) was archdeacon and schoolmaster at Angers, France, then Bishop of Rennes in Brittany. He was a respected poet, hagiographer, and hymnologist. Biography Marbod was born near Angers ...

recommended malachite as a talisman for young people because of its protective qualities and its ability to help with sleep.The Book of Talismans, Amulets and Zodiacal Gems, by William Thomas and Kate Pavitt,

922 __NOTOC__ Year 922 ( CMXXII) was a common year starting on Tuesday (link will display the full calendar) of the Julian calendar. Events By place Byzantine Empire * Summer – Battle of Constantinople: Emperor Romanos I sends Byza ...

p. 254 It has also historically been worn for protection from lightning and contagious diseases and for health, success, and constancy in the affections. During the Middle Ages it was customary to wear it engraved with a figure or symbol of the Sun to maintain health and to avert depression to which Capricorns were considered vulnerable. In ancient Egypt the colour green (wadj) was associated with death and the power of resurrection as well as new life and fertility. Ancient Egyptians believed that the

afterlife The afterlife (also referred to as life after death) is a purported existence in which the essential part of an individual's identity or their stream of consciousness continues to live after the death of their physical body. The surviving ess ...

contained an eternal paradise, referred to as the "Field of Malachite", which resembled their lives but with no pain or suffering.

Ore uses

Simple methods of copper ore extraction from malachite involved thermodynamic processes such as smelting. This reaction involves the addition of heat and a carbon, causing the carbonate to decompose leaving copper oxide and an additional carbon source such as coal converts the copper oxide into copper metal. The basic word equation for this reaction is: Copper carbonate + heat → carbon dioxide + copper oxide (color changes from green to black). Copper oxide + carbon → carbon dioxide + copper (color change from black to copper colored). Malachite is a low grade copper ore, however, due to increase demand for metals, more economic processing such as hydrometallurgical methods (using aqueous solutions such as

sulfuric acid Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid ( Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen and hydrogen, with the molecular formu ...

) are being used as malachite is readily soluble in dilute acids.

Sulfuric acid Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid ( Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen and hydrogen, with the molecular formu ...

is the most common leaching agent for copper oxide ores like malachite and eliminates the need for smelting processes. The chemical equation for sulfuric acid leaching of copper ore from malachite is as follows:

Health and environmental concerns

Mining for malachite for ornamental or copper ore purposes involves open-pit mining or underground mining depending on the grade of the ore deposits. Open-pit and underground mining practices can cause

environmental degradation Environmental degradation is the deterioration of the environment (biophysical), environment through depletion of resources such as quality of air, water and soil; the destruction of ecosystems; habitat destruction; the extinction of wildlife; an ...

through habitat and biodiversity loss. Acid mine drainage can contaminate water and food sources to negatively impact human health if improperly managed or if leaks from

tailing ponds In mining, tailings are the materials left over after the process of separating the valuable fraction from the uneconomic fraction (gangue) of an ore. Tailings are different to overburden, which is the waste rock or other material that overlie ...

occur. The risk of health and environmental impacts of both traditional metallurgy and newer methods of hydrometallurgy are both significant, however, water conservation and waste management practices for hydrometallurgy processes for ore extraction, such as for malachite, are stricter and relatively more sustainable. New research is also being conducted on better alternatives to methods such as sulfuric acid leaching which has high environmental impacts, even under hydrometallurgy regulation standards and innovation.

Gallery

File:Malachite-41365.jpg, Slice through a double

stalactite A stalactite (, ; from the Greek 'stalaktos' ('dripping') via ''stalassein'' ('to drip') is a mineral formation that hangs from the ceiling of caves, hot springs, or man-made structures such as bridges and mines. Any material that is soluble an ...

, from Kolwezi, Democratic Republic of the Congo. Size 5.9 × 3.9 × 0.7 cm. File:Azurite-Malachite-163967.jpg, Malachite and azurite from Bisbee,

Warren District Warren, also known as Karri Forest Region and the Jarrah-Karri forest and shrublands ecoregion, is a biogeographic region in southern Western Australia. Located in the southwest corner of Western Australia between Cape Naturaliste and Albany, i ...

, Mule Mts, Cochise County, Arizona File:Malachite-153552.jpg, Malachite stalactites (to 9 cm height), from Kasompi Mine,

Katanga Province Katanga was one of the four large provinces created in the Belgian Congo in 1914. It was one of the eleven provinces of the Democratic Republic of the Congo between 1966 and 2015, when it was split into the Tanganyika Province, Tanganyika, Hau ...

, Democratic Republic of the Congo. Size: 21.6×16.0×11.9 cm. File:Malachite, da rep. dem. congo.JPG, Sample of malachite found at Kaluku Luku Mine, Lubumbashi, Shaba, Congo File:Ermitáž (32).jpg, Vase in malachite in the Hermitage Museum, St Petersburg File:Malachite, image taken under a stereoscopic microscope.jpg, Malachite, image taken under a stereoscopic microscope File:Calendar (part of a set) MET DP-13486-011.jpg , British calendar, 1851, gilt bronze and malachite, height: 20.3 cm, Metropolitan Museum of Art (New York City) File:Elephant in malachite Length 11 cm arp.jpg, Elephant carved from malachite. Length 11 cm.

References

External links

Virtual tour of the Malachite Room

Malachite
Colourlex
Malachite in art and malachite diplomacy
{{Authority control Carbonate minerals Copper ores Gemstones Inorganic pigments Minerals in space group 14 Monoclinic minerals