Paramelaconite

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Paramelaconite
Paramelaconite-304492.jpg
Paramelaconite from the Copper Queen Mine, Cochise County, Arizona, USA
General
Category Oxide mineral
Formula
(repeating unit)		CuI
2CuII
2O3 [1] (or Cu4O3) [2]
IMA symbol Pml [3]
Strunz classification 4.AA.15
Dana classification4.6.4.1
Crystal system Tetragonal
Crystal class Ditetragonal dipyramidal (4/mmm)
H-M group: (4/m 2/m 2/m)
Space group I41/amd {I41/a 2/m 2/d}
Unit cell a = 5.837 Å,
c = 9.932 Å; Z = 4 [1]
Identification
ColorBlack to black with a slight purple tint
White with pinkish brown tint in reflected light
Crystal habit Occurs as striated prismatic crystals; massive
Cleavage None observed
Fracture Conchoidal
Tenacity Brittle
Mohs scale hardness4.5
Luster Sub-adamantine, greasy, sub-metallic
Streak Brown-black
Diaphaneity Opaque
Specific gravity 6.04–6.11 (measured)
Optical propertiesUniaxial [1]
Pleochroism Weak
Ultraviolet fluorescence Not fluorescent
Solubility Soluble in HCl and HNO3 [4]
References [5]

Paramelaconite is a rare, black-colored copper(I,II) oxide mineral with formula CuI
2CuII
2O3 (or Cu4O3). It was discovered in the Copper Queen Mine in Bisbee, Arizona, about 1890. It was described in 1892 and more fully in 1941. Its name is derived from the Greek word for "near" and the similar mineral melaconite, now known as tenorite.

Contents

Description and occurrence

Type material from the Copper Queen Mine held at the A. E. Seaman Mineral Museum Paramelaconite.jpg
Type material from the Copper Queen Mine held at the A. E. Seaman Mineral Museum

Paramelaconite is black to black with a slight purple tint in color, and is white with a pinkish brown tint in reflected light. The mineral occurs with massive habit or as crystals up to 7.5 cm (3 in). [1] A yellow color is formed when the mineral is dissolved in hydrochloric acid, a blue color when dissolved in nitric acid, and a slightly brown precipitate when exposed to ammonium hydroxide. [4] When heated, paramelaconite breaks down into a mixture of tenorite and cuprite. [6]

Paramelaconite is a very rare mineral; many specimens purported as such are in fact mixtures of cuprite and tenorite. [7] Paramelaconite forms as a secondary mineral in hydrothermal deposits of copper. It occurs in association with atacamite, chrysocolla, connellite, cuprite, dioptase, goethite, malachite, plancheite, and tenorite. [1] The mineral has been found in Cyprus, the United Kingdom, and the United States. [5]

Structure

Paramelaconite crystallizes in the tetragonal crystal system. [5] Its space group was correctly identified by Frondel as I41/amd. In 1978, O'Keeffe and Bovin determined the formula to be Cu4O3, specifically CuI
2CuII
2O3. There has been misunderstanding and misreporting of the mineral's crystal structure, due in part to a typographical error in O'Keeffe and Bovin's paper and the commonality of choosing an incorrect origin for the I41/amd space group. [2] At the same time as O'Keeffe and Bovin's report, a paper by Datta and Jeffery determined a structure for the mineral based on the incorrect formula CuII
12CuI
4O14. [2] [8] The formula originated from incorrectly assuming that Frondel's analysis was of a homogeneous crystal of paramelaconite. [2]

Synthesis

The synthesis of microscopic paramelaconite was reported in 1986 as a product of the decomposition of CuO in an electron microscope. However, this method is not easily scaled up to produce samples large enough for study. Reduction of CuO and decomposition in a vacuum and controlled oxidation of Cu2O failed to synthesize the mineral. Experiments at the National Bureau of Standards using aqueous solutions up to 250 °C produced only Cu2O and CuO. Oxidation of copper or its alloys also does not produce paramelaconite, despite reports to the contrary. [9]

The first unequivocal synthesis of the mineral was achieved in the 1990s and published in 1996. The material produced was 35% Cu4O3, 27% Cu2O, and 38% CuO. [2] The process consists of the leaching of copper or its oxides with concentrated aqueous ammonia in a Soxhlet extractor. The reaction forms a deep blue complex of cupric ammonium that is converted to a residue of black oxide in the apparatus. [9]

History

Drawing of a specimen found by Foote; the center pyramid is paramelaconite Paramelaconite - Copper Queen Mine.JPG
Drawing of a specimen found by Foote; the center pyramid is paramelaconite

Albert E. Foote visited the Copper Queen Mine about 1890, [10] where he obtained two specimens containing unknown minerals. He could only associate them with anatase, but he thought it unlikely that the minerals were any form of titanium oxide. [11] The specimens were sold to Clarence M. Bement at fifty dollars apiece, and with his permission, were studied by George Augustus Koenig. [10] [11] Bement's collection, including the specimens of paramelaconite, were purchased by J. P. Morgan in 1900 and given to the American Museum of Natural History. [2] [10]

Owing to its unique appearance, Koenig assigned the mineral as a new species. [12] His description of the mineral appeared in an 1892 publication of the Academy of Natural Sciences of Philadelphia. [11] He named the mineral paramelaconite from the Greek παρά, meaning "near", and the mineral melaconite (now known as tenorite), for its compositional similarity to melaconite. [5] [11] At the time, however, the mineral was not recognized as a valid species. [10]

Clifford Frondel studied the mineral in more detail and published his results in the journal American Mineralogist in 1941. [7] [13] When the International Mineralogical Association was founded in 1959, paramelaconite was grandfathered as a valid mineral species. [5] In the early 1960s, the third known specimen of paramelaconite was discovered from the Copper Queen Mine; Koenig donated it to the A. E. Seaman Mineral Museum. Other specimens in the museum, labeled as originating from the Algomah Mine in Ontonagon County, Michigan, were also found to contain paramelaconite. [14]

The type material is held at the A. E. Seaman Mineral Museum in Houghton, Michigan, the American Museum of Natural History in New York City, Harvard University in Cambridge, Massachusetts, the National Museum of Natural History in Washington, D.C., and the Natural History Museum in London. [1]

Related Research Articles

Chalcopyrite Copper iron sulfide mineral

Chalcopyrite ( KAL-kə-PY-ryte, -⁠koh-) is a copper iron sulfide mineral and the most abundant copper ore mineral. It has the chemical formula CuFeS2 and crystallizes in the tetragonal system. It has a brassy to golden yellow color and a hardness of 3.5 to 4 on the Mohs scale. Its streak is diagnostic as green tinged black.

Bornite

Bornite, also known as peacock ore, is a sulfide mineral with chemical composition Cu5FeS4 that crystallizes in the orthorhombic system (pseudo-cubic).

Azurite Copper carbonate mineral

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 at Chessy-les-Mines near Lyon, France. The mineral, a basic carbonate with the chemical formula Cu3(CO3)2(OH)2, has been known since ancient times, and was mentioned in Pliny the Elder's Natural History under the Greek name kuanos (κυανός: "deep blue," root of English cyan) and the Latin name caeruleum. Since antiquity, azurite's exceptionally deep and clear blue has been associated with low-humidity desert and winter skies. The modern English name of the mineral reflects this association, since both azurite and azure are derived via Arabic from the Persian lazhward (لاژورد), an area known for its deposits of another deep-blue stone, lapis lazuli ("stone of azure").

Cuprite

Cuprite is an oxide mineral composed of copper(I) oxide Cu2O, and is a minor ore of copper.

Dioptase

Dioptase is an intense emerald-green to bluish-green copper cyclosilicate mineral. It is transparent to translucent. Its luster is vitreous to sub-adamantine. Its formula is Cu6Si6O18·6H2O (also reported as CuSiO2(OH)2). It has a hardness of 5, the same as tooth enamel. Its specific gravity is 3.28–3.35, and it has two perfect and one very good cleavage directions. Additionally, dioptase is very fragile, and specimens must be handled with great care. It is a trigonal mineral, forming 6-sided crystals that are terminated by rhombohedra.

Murdochite

Murdochite is a mineral combining lead and copper oxides with the chemical formula PbCu
6O
8−x(Cl,Br)
2x (x ≤ 0.5).

Copper(II) oxide Chemical compound - an oxide of copper with formula CuO

Copper(II) oxide or cupric oxide is an inorganic compound with the formula CuO. A black solid, it is one of the two stable oxides of copper, the other being Cu2O or copper(I) oxide (cuprous oxide). As a mineral, it is known as tenorite. It is a product of copper mining and the precursor to many other copper-containing products and chemical compounds.

Tenorite

Tenorite is a copper oxide mineral with the chemical formula CuO.

Ajoite

Ajoite is a hydrated sodium potassium copper aluminium silicate hydroxide mineral. Ajoite has the chemical formula (Na,K)Cu7AlSi9O24(OH)6·3H2O, and minor Mn, Fe and Ca are usually also present in the structure. Ajoite is used as a minor ore of copper.

Arthurite

Arthurite is a mineral composed of divalent copper and iron ions in combination with trivalent arsenate, phosphate and sulfate ions with hydrogen and oxygen. Initially discovered by Sir Arthur Russell in 1954 at Hingston Down Consols mine in Calstock, Cornwall, England, arthurite is formed as a resultant mineral in the oxidation region of some copper deposits by the variation of enargite or arsenopyrite. The chemical formula of Arthurite is CuFe23+(AsO4,PO4,SO4)2(O,OH)2•4H2O.

Chalcophyllite

Chalcophyllite is a rare secondary copper arsenate mineral occurring in the oxidized zones of some arsenic-bearing copper deposits. It was first described from material collected in Germany. At one time chalcophyllite from Wheal Tamar in Cornwall, England, was called tamarite, but this name is now discredited. At Wheal Gorland a specimen exhibiting partial replacement of liriconite, Cu
2Al(AsO
4)(OH)
4•(4H
2O), by chalcophyllite has been found. The mineral is named from the Greek, chalco "copper" and fyllon, "leaf", in allusion to its composition and platy structure. It is a classic Cornish mineral that can be confused with tabular spangolite.

Calumetite

Calumetite is a natural rarely occurring mineral. It was discovered in 1963 at the Centennial Mine near Calumet, Michigan, United States. Calumetite was first discovered along with anthonyite. It has a chemical formula of Cu(OH,Cl)
2•2(H
2O).

Pseudomalachite

Pseudomalachite is a phosphate of copper with hydroxyl, named from the Greek for “false” and “malachite”, because of its similarity in appearance to the carbonate mineral malachite, Cu2(CO3)(OH)2. Both are green coloured secondary minerals found in oxidised zones of copper deposits, often associated with each other. Pseudomalachite is polymorphous with reichenbachite and ludjibaite. It was discovered in 1813. Prior to 1950 it was thought that dihydrite, lunnite, ehlite, tagilite and prasin were separate mineral species, but Berry analysed specimens labelled with these names from several museums, and found that they were in fact pseudomalachite. The old names are no longer recognised by the IMA.

Anthonyite

Anthonyite is a hydrous secondary copper halide mineral with chemical formula of Cu(OH,Cl)2•3(H2O).

Plancheite

Plancheite is a hydrated copper silicate mineral with the formula Cu8Si8O22(OH)4•(H2O). It is closely related to shattuckite in structure and appearance, and the two minerals are often confused.

Cornubite

Cornubite is a rare secondary copper arsenate mineral with formula: Cu5(AsO4)2(OH)4. It was first described for its discovery in 1958 in Wheal Carpenter, Gwinear, Cornwall, England, UK. The name is from Cornubia, the medieval Latin name for Cornwall. It is a dimorph of Cornwallite, and the arsenic analogue of pseudomalachite.

Diaboleite

Diaboleite is a blue-colored mineral with formula Pb2CuCl2(OH)4. It was discovered in England in 1923 and named diaboleite, from the Greek word διά and boleite, meaning "distinct from boleite". The mineral has since been found in a number of countries.

Marshite

Marshite (CuI) is a naturally occurring isometric halide mineral with occasional silver (Ag) substitution for copper (Cu). Solid solution between the silver end-member miersite and the copper end-member marshite has been found in these minerals from deposits in Broken Hill, Australia. The mineral's name is derived from the person who first described it, an Australian mineral collector named Charles W. Marsh. Marsh drew attention to native copper iodide (Marshite) in the 1800s emphasizing its natural occurrence, it is not to be confused with copper (I) iodide a substance commonly synthesized in laboratory settings.

Chalconatronite

Chalconatronite is a carbonate mineral and rare secondary copper mineral that contains copper, sodium, carbon, oxygen, and hydrogen, its chemical formula is Na2Cu(CO3)2•3(H2O). Chalconatronite is partially soluble in water, and only decomposes, although chalconatronite is soluble while cold, in dilute acids. The name comes from the mineral's compounds, copper ("chalcos" in Greek) and natron, naturally forming sodium carbonate. The mineral is thought to be formed by water carrying alkali carbonates (possibly from soil) reacting with bronze. Similar minerals include malachite, azurite, and other copper carbonates. Chalconatronite has also been found and recorded in Australia, Germany, and Colorado.

Euchlorine (KNaCu3(SO4)3O) is a rare emerald-green colored sulfate mineral found naturally occurring as a sublimate in fumaroles around volcanic eruptions. It was first discovered in fumaroles of the 1868 eruption at Mount Vesuvius in Campania, Italy by Arcangelo Scacchi. The name 'euchlorine' comes from the Greek word εΰχλωρος meaning "pale green" in reference to the mineral's color, other reported spellings include euclorina, euchlorin, and euchlorite.

References

  1. 1 2 3 4 5 6 Anthony, John W.; Bideaux, Richard A.; Bladh, Kenneth W.; Nichols, Monte C. (eds.). "Paramelaconite" (PDF). Handbook of Mineralogy. Chantilly, VA: Mineralogical Society of America.
  2. 1 2 3 4 5 6 Morgan et al. 1996, p. 33.
  3. ↑ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85: 291–320.
  4. 1 2 Koenig 1892, p. 287.
  5. 1 2 3 4 5 "Paramelaconite". Mindat. Retrieved September 3, 2012.
  6. ↑ Frondel 1941, pp. 657–658.
  7. 1 2 O'Keeffe & Bovin 1978, p. 180.
  8. ↑ Datta & Jeffery 1978, p. 22.
  9. 1 2 Morgan et al. 1996, p. 35.
  10. 1 2 3 4 Frondel 1941, p. 658.
  11. 1 2 3 4 Koenig 1892, p. 284.
  12. ↑ Koenig 1892, p. 289.
  13. ↑ Frondel 1941, p. 657.
  14. ↑ Williams 1962, p. 778.

Bibliography

Further reading

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