Good Malachite (Copper Carbonate Hydroxide) Term Paper Example

{Author Name [first-name middle-name-initials last-name]}
{Institution Affiliation [name of Author’s institute]}

Abstract 3

Introduction 4
Literature Review: 4
The physical and chemical properties of Malachite 4
Copper carbonate hydroxide Applications 7
Toxicological review of Malachite 8
Conclusion 9

References 10

Abstract
Malachite is a copper carbonate hydroxide compound naturally present in water surfaces above the copper deposits. It’s a divalent copper compound with a chemical composition of Cu2(CO3)(OH)2. Due to its distinct idiochromatic coloration it is used in sculpture, coloring agents and other industrial uses including algaecides and microbicide development, antibiotics, and textile industry. It has toxic effects due to the form of Cu as Cu2+ cation present in its composition. Cu exerts toxic effects on mammals, aquatic organism, and microbes’ development. Due to is toxic potential it is used in microbicides and algaecides in fish farming and aquaculture, which is the main reason for Cu contamination in natural water. The chronic exposure of Cu results in adverse effects on aquatic animals that include growth reduction, tissue damage, carcinogenic and mutagenic effects in fish. In this review, the basic properties and effects of Malachite on the environment are discussed.
Introduction
Malachite is copper carbonate hydroxide, and its chemical composition is Cu2(CO3)(OH)2. 1 It is a relative soft at the natural stage with beautiful green shades. Due to its green color it is used in sculpture, jewelry, coloring agents and other industrial uses. Additional applications are, as a catalyst, food additive, insecticide, antidote, and desulfurizer.1,2 It has shown toxicological effects on aquatic life. For this reason, it has become an area of interest for geologist and ecologists to interpret its adverse effect on aquatic lives as well as lives on land. Malachite is also treated as semi precious gemstone and used for jewelry purpose. 2
Malachite has been used in sculptural work from earliest civilizations and in artworks from the medieval period. The history of Malachite starts since mid of 18th century. Its color varies from light green to dark green, often with streak of lighter shades. The presence of Copper in its formulation and crystal composition provides it idiochromatic coloration. Large crystals of Malachite are rare and occur in prismatic forms. Its aggregates are found in the mammillary, botryoidal or globular shapes with smooth and protruding masses. They possess radial layers with diverse colors and concentric rings which offer it a beautiful exterior.2, 3
This literature review focuses on the properties of Malachites, its origin areas, application areas and recent research conducted on malachite. It presents a toxicological review of malachite in water.
Literature Review:
The physical and chemical properties of Malachite
The Malachite, a copper oxide mineral contains copper in the divalent state.1 It has a unique crystal system that possesses three axes of uneven lengths. Two axes are perpendicular to each other. This feature gives it a distorted octahedral shape. In the crystal structure of malachite Cu2+ cation is an octahedron made of OH- and O2- anions (Fig 1). The octahedron contains four anions of one type and two of another type. These octahedrons are bound to each other and form chains through linking carbonate groups. The Raman spectra of malachite are very complex exhibiting a lot of bands which may be due to the distorted octahedral arrangement of Cu in its crystal. 4
Figure 1: Malachite crystal (Copper Carbonate Hydroxide)
The total substance ratio shows 55% copper in from of oxide in the malachite. It is a crystalline powder that is completely soluble either in acid or alkaline medium but insoluble in water. 1 At the temperature of 220 it breaks down, and its melting point is 200℃. Molecular weight of malachite is 221.13. Malachite is a secondary copper mineral that demonstrate high variability in its pattern. It is found in the form of crusts or crystalline aggregates while it also appears in striped forms such as agates. XRD analysis of malachite after ammonium carbonate based leaching indicated that it was completely dissolvable that increased the content of other minerals in an ore. The leaching of Cu ore through dissolving approach has produced malachite 49.9 %, 22.6% magnetite and goethite and 27.4% quartz. 1 In understanding the dissolution kinetics of malachite using sulphuric acid, leaching is described through these reactions: 3
Cu3 (OH)2(CO3)2 + 3H2SO4 → 3CuSO4 + 2CO2 + 4H2
Cu2(OH)2CO3 + 2H2SO4 → 2CuSO4 + CO2 + 3H2O
CuO + H2SO4 → CuSO4 + H2O
CuSiO3.2H2O + H2SO4 → CuSO4 + SiO2 + 3H2O
In this method, the copper recovery from malachite was 94% and 99% at 25 oC and 80 oC, respectively, on applying leaching for 180 minutes. 3According to Hernandez, the strong antiferromagnetic pairing exists in the large Cu-O-Cu bridging angles in copper secondary mineral.5
Figure 2: Malachite stone, powder form, and as copper ore
Presence of malachite indicates the copper deposits in depth. It is found in dry or semi-arid oxidizing zones in the shallow nadir, near the surface. It is formed due to precipitation occurring in fractures and interspaces of porous rocks. Limestone is also a favorable place for carbonates mineral precipitation. Earlier malachite deposits were found near Egypt and Israel, Ural Mountains of Russia.6,7 According to the literature, malachite in association with zinc carbonates at Ophir illustrated two types of appearance. A type is formed by replacing lamellar smithsonite and the second type showed development as druses in cavities of smithsonite. The advancement towards purity of malachite can be defined from spotty appearance to the streaks preserving the former lamellar structure of smithsonite. The thin areas showing spots or streaks demonstrate the part containing replaced grains of smithsonite and enclosed granule of calcite. The thorough analysis shows these thin areas are made of minute radiating groups of malachite needles. In the center of these groups, fragments of ferric oxide exist. The polygonal outline enclosing these units gives it a shape of corals. The current source of malachite for lapidary industry is Democratic Republic of the Congo, France, Australia, and Arizona. 6,7,8
The unique property of idiochromatic coloration led to the identification and analysis of characteristic of malachite. According to a research simple carbonate of copper does not exist in natural minerals, malachite is basic carbonate containing one part of carbonate (CuCO3) and one part of hydrate (CuO2H2). Malachite has high resemblance with Azurite minerals that also a basic carbonate with two times carbonate (CuCO3) against hydrate (CuO2H2). The solution that replaced smithsonite with malachite in zinc carbonate ore at Ophir is copper sulfate.9,10 Now malachite availability is scarce, but it can be prepared in the labs under appropriate conditions.1,2,10
Copper carbonate hydroxide Applications
Malachite is often known as basic copper carbonate (Cu2CO3(OH)2), which is used in respiratory filters to saturate the activated carbons. 11 The main characteristic of malachite is its color that’s why it is used in dyes industry and cosmetic industry as well. The toxicological effects of malachite have made it essential as algaecide in fish farming and aquaculture. It is also used as antibiotic agents, fungicides, and microbicides.1,2,5,7
Toxicological review of Malachite
Copper compounds are essential in for the environment, plants, and animals but toxic to microbes. The copper (Cu2+) cation present freely or in the form of minerals in water resources is toxic for aquatic life. Malachite is found near shallow water above the copper deposits that is a significant source of intense chronic toxicity.12,13 Higher the water softness higher is the toxicity in the water. The concentration of dissolved oxygen in water also influences the toxicity inversely. pH and alkalinity, organic compounds and suspended solids of water impacts copper originated toxicity. Copper compounds bio-accumulate in the tissues of aquatic animals. The copper associated with carbonate and hydroxide ions in cupric carbonate determines the copper concentration in the water. Based on all parameters including alkalinity, pH, hardness of water and concentration of copper and carbonic compounds determine the tolerable quantity of copper for aquatic organisms. 12,13 The lab results available earlier had shown a negative impact on insect while field data were presenting positive impact. This ambivalence led to a thorough analysis of metallic influence on aquatic insects. Brix conducted a study on insects to identify the toxic impact level of copper and other metals on insects.14 They suggested that aquatic insects are insensitive to acute exposures while several aquatic insect have shown high sensitivity towards chronic exposure to metal. The main reason for this discrepancy was difference of period of exposure. In lab studies due to the short time, exposure insects responded with low sensitivity while they face a prolonged chronic exposure to metals in field studies.14 Apart from this in the field aquatic insects are affected directly through interference of metals with the food chain. Current evidences propose that food is the primary source of metal accumulation causing toxicity in insects. 14
The digestible concentration of Cu for an adult human is 1.2 milligrams per day while lethal dose is 10-20 gm. It is highly toxic at high levels.15 Cu is a substance of algaecides and herbicides that is used in fish farming and aquaculture, through this medium Cu reaches the aquatic organisms including plants, bacteria, fish, and other marine animals. A study revealed that the Cu below the concentration 2mg/L can block the olfactory senses in several fishes. Another research claimed that the Cu exposure for four weeks at the concentration of 9-10 µg/L can reduce the growth in amphipod Allorchestes compressa.15
The toxicity of Cu is highest when it is as free Cu+ and Cu2+ ion. The inorganic and organic forms of Cu are not much toxic. The formation of carbonates and hydroxide by free Cu in water reduces its toxicity against marine organisms. Copper toxicity in the water and environment is a rising issue of the current time, worldwide. 15
Conclusion
Malachite or basic copper carbonate hydroxide or cupric carbonate is a divalent copper compound. It has a green color which gives it an attractive manifestation and makes it appropriate for artwork, jewelry, color pigment formation, and sculpture work. This literature review emphasizes on the physical and chemical features of malachite that are useful and harmful as well. The discrepancy in its effects depends on the period of exposure and concentration of the compound.
References
Bingöl, D.; Canbazoğlu, M.; Aydoğan, S. Hydrometallurgy 2005, 76(1), 55-62.
King, H. Malachite | Mineral, Gemstone, Uses and Properties http://geology.com/minerals/malachite.shtml (accessed Mar 21, 2015).
Bingöl, D.; Canbazoğlu, M. Hydrometallurgy 2004, 72, 159-165.
Frost, RL.; Martens, WN.; Rintoul, L.; Mahmutagic, E.; Kloprogge, JT. Journal of Raman Spectroscopy 2001, 33, 252-259.
Gil-Hernandez, B.; Gili, P.; Pasán, J.; Sanchiz, J.; Ruiz-Pérez, C. CrystEngComm 2012, 14, 4289.
Gill, R. Chemical Fundamentals of Geology and Environmental Geoscience; Wiley: Hoboken, 2014.
Cook, R. B.; Rocks & Minerals 2009, 84(1), 48-53.
Army, M.; Cambridge Univ Press
Liversidge, A.; The Minerals of New South Wales 2011. Etc. Cambridge University Press.
Colman, T. (2012). Australia’s metalliferous mineral wealth. MERCIAN GEOLOGIST, 18(1), 6.
Smith, J. W. H., Westreich, P., Croll, L. M., Reynolds, J. H., & Dahn, J. R. (2009). Understanding the role of each ingredient in a basic copper carbonate based impregnation recipe for respirator carbons. Journal of colloid and interface science, 337(2), 313-321.
El-Moselhy, KM.; Mohamedein, LI.; Abdelmoneim, MA. African J. Biol. Sci 2011, 7, 13-21.
Npi.gov.au, Copper and compounds | National Pollutant Inventory http://www.npi.gov.au/resource/copper-and-compounds (accessed Mar 24, 2015).
Brix, K.; DeForest, D.; Adams, W. Science of The Total Environment 2011, 409, 4187-4197.
Palmer, J.; The Plymouth Student Scientist 2014, 7(2), 151-184.