Malachite () is a

copper Copper is a chemical element; it has symbol Cu (from Latin ) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orang ...

carbonate A carbonate is a salt of carbonic acid, (), characterized by the presence of the carbonate ion, a polyatomic ion with the formula . The word "carbonate" may also refer to a carbonate ester, an organic compound containing the carbonate group ...

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 betwe ...

Cu₂CO₃(OH)₂. This opaque, green-banded mineral crystallizes in the

monoclinic crystal 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 sy ...

, and most often forms botryoidal, fibrous, or stalagmitic 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.

Pseudomorph In mineralogy, a pseudomorph is a mineral or mineral compound that appears in an atypical form (crystal system), resulting from a substitution process in which the appearance and dimensions remain constant, but the original mineral is replaced b ...

s after more tabular or blocky

azurite Azurite or '' Azure spar'Krivovichev V. G.'' Mineralogical glossary. Scientific editor A. G. Bulakh. — St.Petersburg: St.Petersburg Univ. Publ. House. 2009. — 556 p. — ISBN 978-5-288-04863-0. ''(in Russian)'' is a soft, deep-blue copp ...

crystals also occur.

Etymology and history

The stone's name derives (via , , and

Middle English Middle English (abbreviated to ME) is a form of the English language that was spoken after the Norman Conquest of 1066, until the late 15th century. The English language underwent distinct variations and developments following the Old English pe ...

''melochites'') from

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

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. Copper (Cu²⁺) gives malachite its green color. 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 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 Israel, officially the State of Israel, is a country in West Asia. It Borders of Israel, shares borders with Lebanon to the north, Syria to the north-east, Jordan to the east, Egypt to the south-west, and the Mediterranean Sea to the west. Isr ...

for more than 3,000 years. Since then, malachite has been used as both an ornamental stone and as a gemstone. The use of

and malachite as copper ore indicators led indirectly to the name of the element

nickel Nickel is a chemical element; it has symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive, but large pieces are slo ...

in the English language.

Nickeline Nickeline or niccolite is the mineral form of nickel arsenide. The naturally-occurring mineral contains roughly 43.9% nickel and 56.1% arsenic by mass, but composition of the mineral may vary slightly. Small quantities of sulfur, iron and cobalt ...

, a principal ore of nickel that is also known as niccolite, weathers at the surface into a green mineral (

annabergite Annabergite is an arsenate mineral consisting of a hydrous nickel arsenate. It is considered a member of the vivianite group and known for its ability to form crystals in a characteristic apple-green color. History Annabergite has been kn ...

) that resembles malachite. This resemblance resulted in occasional attempts to smelt nickeline in the belief that it was copper ore, but such attempts always ended in failure due to high smelting temperatures needed to reduce nickel. In Germany this deceptive mineral came to be known as ''kupfernickel'', literally "copper

demon A demon is a malevolent supernatural entity. Historically, belief in demons, or stories about demons, occurs in folklore, mythology, religion, occultism, and literature; these beliefs are reflected in Media (communication), media including f ...

." The Swedish

alchemist Alchemy (from the Arabic word , ) is an ancient branch of natural philosophy, a philosophical and protoscientific tradition that was historically practised in China, India, the Muslim world, and Europe. In its Western form, alchemy is first ...

Baron

Axel Fredrik Cronstedt Baron Axel Fredrik Cronstedt (''/kroonstet/'' 23 December 1722 – 19 August 1765) was a Sweden, Swedish Mineralogy, mineralogist and chemist who discovered the Chemical element, element nickel in 1751 as a mining expert with the Bureau of Mines. ...

(who had been trained by Georg Brandt, the discoverer of the nickel-like metal

cobalt Cobalt is a chemical element; it has Symbol (chemistry), symbol Co and atomic number 27. As with nickel, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural meteoric iron. ...

) realized that there was probably a new metal hiding within the kupfernickel ore, and in 1751 he succeeded in smelting kupfernickel to produce a previously unknown (except in certain

meteorites A meteorite is a rock that originated in outer space and has fallen to the surface of a planet or moon. When the original object enters the atmosphere, various factors such as friction, pressure, and chemical interactions with the atmospheri ...

) silvery white, iron-like metal. Logically, Cronstedt named his new metal after the ''nickel'' part of ''kupfernickel''.

Occurrence

Malachite often results from the supergene 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 Work ...

sulfidic

ore Ore is natural rock or sediment that contains one or more valuable minerals, typically including metals, concentrated above background levels, and that is economically viable to mine and process. The grade of ore refers to the concentration ...

s, and is often found with

(Cu₃(CO₃)₂(OH)₂),

goethite Goethite (, ) is a mineral of the diaspore group, consisting of iron(III) oxide-hydroxide, specifically the α- polymorph. It is found in soil and other low-temperature environments such as sediment. Goethite has been well known since ancient t ...

, 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

and is typically associated with copper deposits around

limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...

s, the source of the carbonate. Large quantities of malachite have been mined in the

Urals The Ural Mountains ( ),; , ; , or simply the Urals, are a mountain range in Eurasia that runs north–south mostly through Russia, from the coast of the Arctic Ocean to the river Ural (river), Ural and northwestern Kazakhstan.

Russia Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...

. Ural malachite is not being mined , 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 The Democratic Republic of the Congo (DRC), also known as the DR Congo, Congo-Kinshasa, or simply the Congo (the last ambiguously also referring to the neighbouring Republic of the Congo), is a country in Central Africa. By land area, it is t ...

;

Gabon Gabon ( ; ), officially the Gabonese Republic (), is a country on the Atlantic coast of Central Africa, on the equator, bordered by Equatorial Guinea to the northwest, Cameroon to the north, the Republic of the Congo to the east and south, and ...

;

Zambia Zambia, officially the Republic of Zambia, is a landlocked country at the crossroads of Central Africa, Central, Southern Africa, Southern and East Africa. It is typically referred to being in South-Central Africa or Southern Africa. It is bor ...

;

Tsumeb Tsumeb (; ) is a city of around 35,000 inhabitants and the largest town in the Oshikoto Region, Oshikoto region in northern Namibia. Tsumeb, since its founding in 1905, has been primarily a mining town. The town is the site of a deep mine (the ...

Namibia Namibia, officially the Republic of Namibia, is a country on the west coast of Southern Africa. Its borders include the Atlantic Ocean to the west, Angola and Zambia to the north, Botswana to the east and South Africa to the south; in the no ...

;

Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...

;

Broken Hill, New South Wales Broken Hill is a city in the Far West (New South Wales), far west region of outback New South Wales, Australia. An inland mining city, it is near the border with South Australia on the crossing of the Barrier Highway (A32) and the Silver City Hi ...

;

Burra, South Australia Burra is a pastoral centre and historic tourist town in the mid-north of South Australia. It lies east of the Clare Valley in the Bald Hills range, part of the northern Mount Lofty Ranges, and on Burra Creek (South Australia), Burra Creek. The t ...

;

Lyon Lyon (Franco-Provençal: ''Liyon'') is a city in France. It is located at the confluence of the rivers Rhône and Saône, to the northwest of the French Alps, southeast of Paris, north of Marseille, southwest of Geneva, Switzerland, north ...

France France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...

; Timna Valley,

; and the

Southwestern United States The Southwestern United States, also known as the American Southwest or simply the Southwest, is a geographic and cultural list of regions of the United States, region of the United States that includes Arizona and New Mexico, along with adjacen ...

, most notably in

Arizona Arizona is a U.S. state, state in the Southwestern United States, Southwestern region of the United States, sharing the Four Corners region of the western United States with Colorado, New Mexico, and Utah. It also borders Nevada to the nort ...

Anthropogenic Anthropogenic ("human" + "generating") is an adjective that may refer to: * Anthropogeny, the study of the origins of humanity Anthropogenic may also refer to things that have been generated by humans, as follows: * Human impact on the enviro ...

malachite was historically believed to be the primary component of the

patina Patina ( or ) is a thin layer that variously forms on the surface of copper, brass, bronze, and similar metals and metal alloys ( tarnish produced by oxidation or other chemical processes), or certain stones and wooden furniture (sheen prod ...

which forms on

and copper alloy structures exposed to open-air

weathering Weathering is the deterioration of rocks, soils and minerals (as well as wood and artificial materials) through contact with water, atmospheric gases, sunlight, and biological organisms. It occurs '' in situ'' (on-site, with little or no move ...

; however, atmospheric sources of sulfate and chloride (such as air pollution or sea winds) typically favour the formation of brochantite or atacamite. Malachite can also be produced synthetically, in which case it is referred to as

basic copper carbonate Basic copper carbonate is a chemical compound, more properly called copper(II) carbonate hydroxide. It can be classified as a coordination polymer or a salt (chemistry), salt. It consists of copper, copper(II) bonded to carbonate and hydroxide ...

or green verditer.

Structure

Malachite crystallizes in the monoclinic system. The structure consists of chains of alternating Cu²⁺

ions An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...

and OH⁻ ions, with a net positive charge, woven between isolated triangular CO₃²⁻ ions. Thus each copper ion is conjugated to two

hydroxyl In chemistry, a hydroxy or hydroxyl group is a functional group with the chemical formula and composed of one oxygen atom covalently bonded to one hydrogen atom. In organic chemistry, alcohols and carboxylic acids contain one or more hydroxy ...

ions and two

ions; each

ion is conjugated with two copper

; 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 In geometry, biology, mineralogy and solid state physics, a unit cell is a repeating unit formed by the vectors spanning the points of a lattice. Despite its suggestive name, the unit cell (unlike a unit vector In mathematics, a unit vector i ...

of malachite File:Malachite-formula-unit-and-coordination-fade-25-from-xtal-3D-bs-17-25.png,

Formula unit In chemistry, a formula unit is the smallest unit of a non-molecular substance, such as an ionic compound, covalent network solid, or metal. It can also refer to the chemical formula for that unit. Those structures do not consist of discrete mol ...

and its coordination environment File:Malachite-xtal-Cu1-coordination-3D-bs-N17-M25.png, Coordination environment 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

File:Malachite-xtal-hydroxide-O4-coordination-3D-bs-N17-M25.png, Coordination environment of

hydroxide Hydroxide is a diatomic anion with chemical formula OH−. It consists of an oxygen and hydrogen atom held together by a single covalent bond, and carries a negative electric charge. It is an important but usually minor constituent of water. It ...

#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, sensitive to

acid An acid is a molecule or ion capable of either donating a proton (i.e. Hydron, hydrogen cation, H+), known as a Brønsted–Lowry acid–base theory, Brønsted–Lowry acid, or forming a covalent bond with an electron pair, known as a Lewis ...

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 wands and the Malachite Room in the

Hermitage Museum The State Hermitage Museum ( rus, Государственный Эрмитаж, r=Gosudarstvennyj Ermitaž, p=ɡəsʊˈdarstvʲɪn(ː)ɨj ɪrmʲɪˈtaʂ, links=no) is a museum of art and culture in Saint Petersburg, Russia, and holds the large ...

, which features a huge malachite vase, and the Malachite Room in

Castillo de Chapultepec Chapultepec Castle () is located on top of Chapultepec Hill in Mexico City's Chapultepec park. The name ''Chapultepec'' is the Nahuatl word which means "on the hill of the grasshopper". It is located at the entrance to Chapultepec park, at a hei ...

Mexico City Mexico City is the capital city, capital and List of cities in Mexico, largest city of Mexico, as well as the List of North American cities by population, most populous city in North America. It is one of the most important cultural and finan ...

. Russian Tsars obtained malachite for decorating their castles, panelling the walls, and for beautiful inlaid works. Another example is the Demidov Vase, part of the former Demidov family collection, and now in the

Metropolitan Museum of Art The Metropolitan Museum of Art, colloquially referred to as the Met, is an Encyclopedic museum, encyclopedic art museum in New York City. By floor area, it is the List of largest museums, third-largest museum in the world and the List of larg ...

. "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 The Linda Hall Library is a privately endowed American library of science, engineering and technology located in Kansas City, Missouri, on the grounds of a urban arboretum. It claims to be the "largest independently funded public library of sc ...

. 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 The Eastern Zhou (256 BCE) is a period in Chinese history comprising the latter two-thirds of the Zhou dynasty. The period follows the Western Zhou era and is named due to the Zhou royal court relocating the capital eastward from Fenghao ...

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 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 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 Ancient Egypt () was a cradle of civilization concentrated along the lower reaches of the Nile River in Northeast Africa. It emerged from prehistoric Egypt around 3150BC (according to conventional Egyptian chronology), when Upper and Lower E ...

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 or life after death is a purported existence in which the essential part of an individual's Stream of consciousness (psychology), stream of consciousness or Personal identity, identity continues to exist after the death of their ...

contained an eternal paradise, referred to as the "Field of Malachite", which resembled their lives but with no pain or suffering. During these times, the green pigment made from malachite was often used for eye preparations during the burial process. These preparations were an essential tool in the funerary equipment, even in modest burials.

Ore uses

Simple methods of copper ore extraction from malachite involved thermodynamic processes such as

smelting Smelting is a process of applying heat and a chemical reducing agent to an ore to extract a desired base metal product. It is a form of extractive metallurgy that is used to obtain many metals such as iron-making, iron, copper extraction, copper ...

. 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 (English in the Commonwealth of Nations, Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen, ...

) 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 (English in the Commonwealth of Nations, Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen, ...

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 Open-pit mining, also known as open-cast or open-cut mining and in larger contexts mega-mining, is a surface mining technique that extracts rock (geology), rock or minerals from the earth. Open-pit mines are used when deposits of commercially ...

underground mining Mining is the extraction of valuable geological materials and minerals from the surface of the Earth. Mining is required to obtain most materials that cannot be grown through agricultural processes, or feasibly created artificially in a la ...

depending on the grade of the ore deposits. Open-pit and underground mining practices can cause

environmental degradation Environment most often refers to: __NOTOC__ * Natural environment, referring respectively to all living and non-living things occurring naturally and the physical and biological factors along with their chemical interactions that affect an organism ...

through

habitat In ecology, habitat refers to the array of resources, biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species' habitat can be seen as the physical manifestation of its ...

and

biodiversity loss Biodiversity loss happens when plant or animal species disappear completely from Earth (extinction) or when there is a decrease or disappearance of species in a specific area. Biodiversity loss means that there is a reduction in Biodiversity, b ...

Acid mine drainage Acid mine drainage, acid and metalliferous drainage (AMD), or acid rock drainage (ARD) is the outflow of acidic water from metal mines and coal mines. Acid rock drainage occurs naturally within some environments as part of the rock weatherin ...

can contaminate water and food sources to negatively impact human health if improperly managed or if leaks from tailing ponds 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 (, ; , ) 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 and that can be deposited as a colloid, or is in suspension (chemistry ...

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

from Bisbee, Warren District, Mule Mts, Cochise County,

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 Lubumbashi ( , ; former ; former ) is the second-largest Cities of the Democratic Republic of the Congo, city in the Democratic Republic of the Congo, located in the country's southeasternmost part, along the border with Zambia. The capital ...

, Shaba, Congo File:Ermitáž (32).jpg, Vase in malachite in the

, 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,

(New York City) File:Malachite at Kaleideum Children's Museum.jpg, Malachite at Kaleideum Children's Museum File:Elephant in malachite Length 11 cm arp.jpg, Elephant carved from malachite. Length 11 cm. File:Malachite-71023.jpg, A polished slice of malachite through three intergrown stalactites with bulls-eye banding

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