Malachite is a

copper Copper is a chemical element with the symbol Cu (from la, cuprum) 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 pinkis ...

carbonate A carbonate is a salt of carbonic acid (H2CO3), 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 g ...

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 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 A botryoidal ( ) texture or mineral habit, is one in which the mineral has an external form composed of many rounded segments, named for the Ancient Greek (), meaning "a bunch of grapes".Adjective form: ''botruoeidēs'' This is a common form f ...

, 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 is a soft, deep-blue copper mineral produced by weathering of copper ore deposits. During the early 19th century, it was also known as chessylite, after the Type locality (geology), type locality at Chessy, Rhône, Chessy-les-Mines near ...

crystals also occur.

Etymology and history

The stone's name derives (via la, molochītis, frm, melochite, 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 p ...

''melochites'') from

Greek Greek may refer to: Greece 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 ...

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 ...

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 The Timna Valley (תִּמְנָע, ) is located in southern Israel in the southwestern Arava/Arabah, approximately north of the Gulf of Aqaba and the city of Eilat. The area is rich in copper ore and has been mined since the 5th millennium ...

Israel Israel (; he, יִשְׂרָאֵל, ; ar, إِسْرَائِيل, ), officially the State of Israel ( he, מְדִינַת יִשְׂרָאֵל, label=none, translit=Medīnat Yīsrāʾēl; ), is a country in Western Asia. It is situated ...

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 weathering and oxidation of primary sulfidic

ore Ore is natural rock or sediment that contains one or more valuable minerals, typically containing metals, that can be mined, treated and sold at a profit.Encyclopædia Britannica. "Ore". Encyclopædia Britannica Online. Retrieved 7 Apr ...

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 ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

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

Urals The Ural Mountains ( ; rus, Ура́льские го́ры, r=Uralskiye gory, p=ʊˈralʲskʲɪjə ˈɡorɨ; ba, Урал тауҙары) or simply the Urals, are a mountain range that runs approximately from north to south through European ...

Russia Russia (, , ), or the Russian Federation, is a List of transcontinental countries, transcontinental country spanning Eastern Europe and North Asia, Northern Asia. It is the List of countries and dependencies by area, largest country in the ...

. 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 The Democratic Republic of the Congo (french: République démocratique du Congo (RDC), colloquially "La RDC" ), informally Congo-Kinshasa, DR Congo, the DRC, the DROC, or the Congo, and formerly and also colloquially Zaire, is a country in ...

;

Gabon Gabon (; ; snq, Ngabu), officially the Gabonese Republic (french: République gabonaise), is a country on the west coast of Central Africa. Located on the equator, it is bordered by Equatorial Guinea to the northwest, Cameroon to the north ...

;

Zambia Zambia (), officially the Republic of Zambia, is a landlocked country at the crossroads of Central Africa, Central, Southern Africa, Southern and East Africa, although it is typically referred to as being in Southern Africa at its most cent ...

;

Tsumeb , nickname = , settlement_type = City , motto = ''Glück Auf'' (German language, German for ''Good luck'') , image_skyline = Welcome to tsumeb.jpg , imagesize = , image_caption ...

Namibia Namibia (, ), officially the Republic of Namibia, is a country in Southern Africa. Its western border is the Atlantic Ocean. It shares land borders with Zambia and Angola to the north, Botswana to the east and South Africa to the south and ea ...

;

Mexico Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...

;

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 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. The town began as a single company ...

;

Lyon Lyon,, ; Occitan: ''Lion'', hist. ''Lionés'' also spelled in English as Lyons, is the third-largest city and second-largest metropolitan area of France. It is located at the confluence of the rivers Rhône and Saône, to the northwest of t ...

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...

;

; 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 Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...

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 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 conven ...

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, for example) does not necessaril ...

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

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. I ...

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 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 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. It is the list of ...

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

Castillo de Chapultepec Chapultepec Castle ( es, Castillo de Chapultepec) is located on top of Chapultepec Hill in Mexico City's Chapultepec park. The name ''Chapultepec'' is the Nahuatl word ''chapoltepēc'' which means "on the hill of the grasshopper". The castle has s ...

Mexico City Mexico City ( es, link=no, Ciudad de México, ; abbr.: CDMX; Nahuatl: ''Altepetl Mexico'') is the capital and largest city of Mexico, and the most populous city in North America. One of the world's alpha cities, it is located in the Valley o ...

. 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 of New York City, colloquially "the Met", is the largest art museum in the Americas. Its permanent collection contains over two million works, divided among 17 curatorial departments. The main building at 1000 ...

. "The Tazza", a large malachite vase, one of the largest pieces of malachite in North America and a gift from

Tsar Nicholas II Nicholas II or Nikolai II Alexandrovich Romanov; spelled in pre-revolutionary script. ( 186817 July 1918), known in the Russian Orthodox Church as Saint Nicholas the Passion-Bearer,. was the last Emperor of Russia, King of Congress Polan ...

, 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, sitting "majestically on a urban arboretum." It is the "largest independently funded public library of scien ...

. 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 (; zh, c=, p=Dōngzhōu, w=Tung1-chou1, t= ; 771–256 BC) was a royal dynasty of China and the second half of the Zhou dynasty. It was divided into two periods: the Spring and Autumn and the Warring States. History In 770 ...

period. The base of

FIFA World Cup Trophy The World Cup is a solid gold trophy that is awarded to the winners of the FIFA World Cup association football tournament. Since the advent of the World Cup in 1930, two trophies have been used: the Jules Rimet Trophy from 1930 to 1970, before ...

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 __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 Following is a list of minerals that serve as copper ores in the copper mining Copper extraction refers to the methods used to obtain copper from its ores. The conversion of copper consists of a series of physical and electrochemical proces ...

extraction from malachite involved thermodynamic processes such as

smelting Smelting is a process of applying heat to ore, to extract a base metal. It is a form of extractive metallurgy. It is used to extract many metals from their ores, including silver, iron, copper, and other base metals. Smelting uses heat and a ch ...

. This reaction involves the addition of heat and a carbon, causing the carbonate to decompose leaving

copper oxide Copper oxide is a compound from the two elements copper and oxygen. Copper oxide may refer to: * Copper(I) oxide (cuprous oxide, Cu2O) * Copper(II) oxide Copper(II) oxide or cupric oxide is an inorganic compound with the formula CuO. A black so ...

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 Open-pit mining, also known as open-cast or open-cut mining and in larger contexts mega-mining, is a surface mining technique of extracting rock or minerals from the earth from an open-air pit, sometimes known as a borrow. This form of mining ...

underground mining Mining is the extraction of valuable minerals or other geological materials from the Earth, usually from an ore body, lode, vein, seam, reef, or placer deposit. The exploitation of these deposits for raw material is based on the economic via ...

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 In ecology, the term habitat summarises the array of resources, physical and 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 ...

and

biodiversity loss Biodiversity loss includes the worldwide extinction of different species, as well as the local reduction or loss of species in a certain habitat, resulting in a loss of biological diversity. The latter phenomenon can be temporary or permanent, de ...

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 or coal mines. Acid rock drainage occurs naturally within some environments as part of the rock weathering ...

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 (, ; 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 Kolwezi or Kolwesi is the capital city of Lualaba Province in the south of the Democratic Republic of the Congo, west of Likasi. It is home to an airport and a railway to Lubumbashi. Just outside of Kolwezi there is the static inverter plant of ...

, 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 Cochise County () is a county in the southeastern corner of the U.S. state of Arizona. It is named after the Native American chief Cochise. The population was 125,447 at the 2020 census. The county seat is Bisbee and the most populous city is ...

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 names: ( French), (Dutch)) is the second-largest city in the Democratic Republic of the Congo, located in the country's southeasternmost part, along the border with Zambia. The capital and principal city of the Haut-Katanga ...

, 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: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