Arthurite

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Arthurite
Arthurite on rock Hydrous basic copper iron arsenate Majuba Hill Pershing County Nevada 2231.jpg
General
Category Arsenate minerals
Formula
(repeating unit)		CuFe23+[(OH,O)(AsO4,PO4,SO4)]2·4H2O
IMA symbol Atu [1]
Strunz classification 8.DC.15
Crystal system Monoclinic
Crystal class Prismatic (2/m)
(same H-M symbol)
Space group P21/c
Unit cell a = 10.189(2), b = 9.649(2)
c = 5.598(1) [Å]
β = 92.16(2)°; Z = 2
Identification
ColorApple-green to bluish-green
Crystal habit Acicular, prismatic, spherical
Mohs scale hardness3–4
Luster vitreous
Streak not reported
Density D(measured) = ~3.2
D(calculated) = 3.29
Optical propertiesBiaxial (+), may be biaxial (–)
Pleochroism X = colorless to pale green; Y = gray-green; Z = olive-green
2V angle ~90°
Dispersion r > v
Absorption spectra Z > Y > X. α = 1.736 β = 1.767 γ = 1.796
Other characteristicsOpacity: transparent to translucent

Arthurite is a mineral composed of divalent copper and iron ions in combination with trivalent arsenate, phosphate and sulfate ions with hydrogen and oxygen. [2] Initially discovered by Sir Arthur Russell in 1954 at Hingston Down Consols mine in Calstock, Cornwall, England, [3] arthurite is formed as a resultant mineral in the oxidation region of some copper deposits by the variation of enargite or arsenopyrite. [2] The chemical formula of Arthurite is Cu Fe 23+(As O 4,P O 4,S O 4)2(O,O H)2·4H 2 O. [4]

Contents

Arthurite is named after Arthur W. G. Kingsbury (1906–1968), a British mineralogist, and Sir Arthur Russell (1878–1964), a collector of minerals.

Introduction

Arthurite was determined to be a uniquely new mineral by R.J. Davis and M.H. Hey in 1964 after its initial discovery. [3] A second specimen was confirmed by A.H Clark and R.H. Sillitoe (1969) from Potrerillos, Atacama Province, Chile in 1969. [5] Subsequently, several other arthurite-like minerals have been discovered. There are variations in which the copper (Cu) ions are replaced with cobalt (Co), in the case of cobaltarthurite, manganese (Mn) replaces Cu in the case of earlshannonite, iron (Fe) in the case of bendadaite and whitmoreite and zinc (Zn) in the case of ojuelaite. Arthurite is the copper-dominant end-member of the arthurite group.

Composition

The theoretical chemical formula of Arthurite was originally determined to be Cu2Fe4(AsO4)3(O,OH)7•6H2O. [3] The breakdown of the composition of arthurite in weight percent oxides is given in Table 1.

Table 1. Chemical composition of Arthurite in weight percent oxides

ElementOxideTheoretical Percentage [3] Recalculated Percentage [6]
CopperCuO16.0014.5
IronFe2O332.1230.1
ArsenicAs2O534.6734.8
HydrogenH2O17.2120.6
Sum96.54100

Arthurite crystallizes from an aqueous solution with whichever applicable anions are accessible in the solution. [2] These available anions may be carbonate, arsenate, sulphate and phosphate. [2] Some other minerals belonging to the arthurite group are cobaltarthurite, Co2+Fe3+2(AsO4)2(OH)2•4H2O, [7] whitmoreite Fe2+Fe3+2(PO4)2(OH)2·4H2O, ojuelaite, ZnFe2(AsO4)2(OH)2·4H2O, earlshannonite, (Mn,Fe)Fe2(PO4)2(OH)2·4H2O [2] and bendadaite, Fe2+Fe3+2(AsO4)2(OH)2·4H2O. [8] The optimal compositions of the members of the arthurite group can be represented by A2+Fe3+2(XO4)2(OH)2·4H2O [9] and are summarized in Table 2.

Table 2. Compositional breakdown of the arthurite group members

MineralA-siteX-siteReference
arthuriteCu2+As5+ [3]
cobaltarthurite Co2+As5+ [9]
whitmoreite Fe2+As5+ [2]
ojuelaite Zn2+P5+ [2]
earlshannonite Mn2+, Fe2+P5+ [2]
bendadaite Fe2+P5+ [8]

Structure

Arthurite is of the monoclinic space group: P21/c with a = 10.189(2)Å, b = 9.649(2)Å, c = 5.598(1)Å and β = 92.16(2). [2] The coordination polyhedron of the Cu2+ ion is clearly tetragonally lengthened as compared to whitmoreite with the Phosphorus (P) and Arsenic (As). [2] Figure 1 shows the crystal structure of arthurite. [10]

Physical properties

Table 3. General and physical properties of arthurite

AttributeData
Chemical formulaCuFe23+(AsO4,PO4,SO4)2(O,OH)2•4H2O
Colorapple-green to bluish green
Opacitytransparent to translucent
Habitacicular, prismatic, spherical
Hardness3–4 (Mohs scale)
LusterVitreous
Optical ClassBiaxial (+), may be biaxial (–)
PleochroismX = colorless to pale green; Y = gray-green; Z = olive-green
OrientationY = b; Z ^ c = 10
AbsorptionZ > Y > X. α = 1.736 β = 1.767 γ = 1.796
DensityD(meas.) = ~3.2 D(calc.) = 3.29
Space groupP21/c. a = 10.189(2) b = 9.649(2) c = 5.598(1) β = 92.16(2)° Z = 2
2V calculation~90°

Geologic occurrence

The first specimen on record was sent to the British Museum of Natural History, Department of Mineralogy by Sir Arthur Russell in 1954. The sample specimen was collected by Sir Russell from Hingston Down Consols mine in Calstock, Cornwall, England. [3] A second sample was found in 1966 in the Potrerillos copper deposit, Atacama Province, northern Chile. [5] Each of these locations have porphyritic copper deposits where circulating groundwater interacts with the cooling porphyritic intrusions and their fluids to form copper-bearing minerals and copper ore deposits. The copper ore found at the Chilean site was composed mainly of massive djurleite deposits that strongly oxidized to form goethite, minor cuprite and malachite. [5] The arthurite formed as thin (0.1 – 0.5 mm) and sparsely coated areas growing along the inner walls of minor fractures splitting through malachite-rich encased djurleite forms. [5]

Biographic sketch

Arthurite is named after two people, Arthur William Gerald Kingsbury and Sir Arthur Edward Ian Montagu Russell. Arthur Kingsbury was the son of a farmer in East Meon, Hampshire, England. He attended Bradfield College in Berkshire prior to an apprenticeship at a London law firm. He passed the bar exam in 1929 and became a solicitor at Sherborne and then later Crewkerne in the West of England. He began collecting minerals in 1927. After the war he accepted a position as a research assistant in the mineralogy department of the Oxford University Museum where he added 50 species to the list of minerals known to occur in Great Britain. [11] Sir Arthur Edward Ian Montagu Russell was born in 1878 and became the 6th Baronet of Swallowfield Park Reading when his older brother died in 1944. Sir Arthur attended the prestigious Eton College and then studied chemistry at King's College, London. During his life he amassed an amazing collection of minerals, many from the collections of others, but also from his own field work. When Sir Arthur died in 1964 his collection of 12,000 mineral specimens went to The Natural History Museum in London with the stipulation that the collection not be dispersed, but remain as a British regional collection. [12]

Related Research Articles

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Jarosite is a basic hydrous sulfate of potassium and ferric iron (Fe-III) with a chemical formula of KFe3(SO4)2(OH)6. This sulfate mineral is formed in ore deposits by the oxidation of iron sulfides. Jarosite is often produced as a byproduct during the purification and refining of zinc and is also commonly associated with acid mine drainage and acid sulfate soil environments.

<span class="mw-page-title-main">Vivianite</span> Phosphate mineral

Vivianite (Fe2+
3(PO
4)
2·8H
2O) is a hydrated iron phosphate mineral found in a number of geological environments. Small amounts of manganese Mn2+, magnesium Mg2+, and calcium Ca2+ may substitute for iron Fe2+ in the structure. Pure vivianite is colorless, but the mineral oxidizes very easily, changing the color, and it is usually found as deep blue to deep bluish green prismatic to flattened crystals.
Vivianite crystals are often found inside fossil shells, such as those of bivalves and gastropods, or attached to fossil bone.

<span class="mw-page-title-main">Torbernite</span> Copper uranyl phosphate mineral

Torbernite, also known as chalcolite, is a relatively common mineral with the chemical formula Cu[(UO2)(PO4)]2(H2O)12. It is a radioactive, hydrated green copper uranyl phosphate, found in granites and other uranium-bearing deposits as a secondary mineral. The chemical formula of torbernite is similar to that of autunite in which a Cu2+ cation replaces a Ca2+ cation. Torbernite tends to dehydrate to metatorbernite with the sum formula Cu[(UO2)(PO4)]2(H2O)8.

<span class="mw-page-title-main">Adamite</span> Zinc arsenate hydroxide mineral

Adamite is a zinc arsenate hydroxide mineral, Zn2AsO4OH. It is a mineral that typically occurs in the oxidized or weathered zone above zinc ore occurrences. Pure adamite is colorless, but usually it possess yellow color due to Fe compounds admixture. Tints of green also occur and are connected with copper substitutions in the mineral structure. Olivenite is a copper arsenate that is isostructural with adamite and there is considerable substitution between zinc and copper resulting in an intermediate called cuproadamite. Zincolivenite is a recently discovered mineral being an intermediate mineral with formula CuZn(AsO4)(OH). Manganese, cobalt, and nickel also substitute in the structure. An analogous zinc phosphate, tarbuttite, is known.

<span class="mw-page-title-main">Copper(II) arsenate</span> Chemical compound

Copper arsenate (Cu3(AsO4)2·4H2O, or Cu5H2(AsO4)4·2H2O), also called copper orthoarsenate, tricopper arsenate, cupric arsenate, or tricopper orthoarsenate, is a blue or bluish-green powder insoluble in water and alcohol and soluble in aqueous ammonium and dilute acids. Its CAS number is 7778-41-8 or 10103-61-4.

In ore deposit geology, supergene processes or enrichment are those that occur relatively near the surface as opposed to deep hypogene processes. Supergene processes include the predominance of meteoric water circulation (i.e. water derived from precipitation) with concomitant oxidation and chemical weathering. The descending meteoric waters oxidize the primary (hypogene) sulfide ore minerals and redistribute the metallic ore elements. Supergene enrichment occurs at the base of the oxidized portion of an ore deposit. Metals that have been leached from the oxidized ore are carried downward by percolating groundwater, and react with hypogene sulfides at the supergene-hypogene boundary. The reaction produces secondary sulfides with metal contents higher than those of the primary ore. This is particularly noted in copper ore deposits where the copper sulfide minerals chalcocite (Cu2S), covellite (CuS), digenite (Cu18S10), and djurleite (Cu31S16) are deposited by the descending surface waters.

<span class="mw-page-title-main">Aheylite</span>

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<span class="mw-page-title-main">Hureaulite</span>

Hureaulite is a manganese phosphate with the formula Mn2+5(PO3OH)2(PO4)2·4H2O. It was discovered in 1825 and named in 1826 for the type locality, Les Hureaux, Saint-Sylvestre, Haute-Vienne, Limousin, France. It is sometimes written as huréaulite, but the IMA does not recommend this for English language text.

<span class="mw-page-title-main">Cornubite</span> Copper arsenate mineral

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<span class="mw-page-title-main">Tsumebite</span>

Tsumebite is a rare phosphate mineral named in 1912 after the locality where it was first found, the Tsumeb mine in Namibia, well known to mineral collectors for the wide range of minerals found there. Tsumebite is a compound phosphate and sulfate of lead and copper, with hydroxyl, formula Pb2Cu(PO4)(SO4)(OH). There is a similar mineral called arsentsumebite, where the phosphate group PO4 is replaced by the arsenate group AsO4, giving the formula Pb2Cu(AsO4)(SO4)(OH). Both minerals are members of the brackebuschite group.

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This list gives an overview of the classification of minerals (silicates) and includes mostly International Mineralogical Association (IMA) recognized minerals and its groupings. This list complements the List of minerals recognized by the International Mineralogical Association series of articles and List of minerals. Rocks, ores, mineral mixtures, non-IMA approved minerals and non-named minerals are mostly excluded.

<span class="mw-page-title-main">Tsumcorite</span>

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<span class="mw-page-title-main">Strashimirite</span>

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<span class="mw-page-title-main">Köttigite</span>

Köttigite is a rare hydrated zinc arsenate which was discovered in 1849 and named by James Dwight Dana in 1850 in honour of Otto Friedrich Köttig (1824–1892), a German chemist from Schneeberg, Saxony, who made the first chemical analysis of the mineral. It has the formula Zn3(AsO4)2·8H2O and it is a dimorph of metaköttigite, which means that the two minerals have the same formula, but a different structure: köttigite is monoclinic and metaköttigite is triclinic. There are several minerals with similar formulae but with other cations in place of the zinc. Iron forms parasymplesite Fe2+3(AsO4)2·8H2O; cobalt forms the distinctively coloured pinkish purple mineral erythrite Co3(AsO4)2·8H2O and nickel forms annabergite Ni3(AsO4)2·8H2O. Köttigite forms series with all three of these minerals and they are all members of the vivianite group.

Copper phosphate may refer to :

<span class="mw-page-title-main">Talmessite</span>

Talmessite is a hydrated calcium magnesium arsenate, often with significant amounts of cobalt or nickel. It was named in 1960 for the type locality, the Talmessi mine, Anarak district, Iran. It forms a series with β-Roselite, where cobalt replaces some of the magnesium, and with gaitite, where zinc replaces the magnesium. All these minerals are members of the fairfieldite group. Talmessite is dimorphic with wendwilsonite.

<span class="mw-page-title-main">Segnitite</span> Common iron oxide mineral

Segnitite is a lead iron(III) arsenate mineral. Segnitite was first found in the Broken Hill ore deposit in Broken Hill, New South Wales, Australia. In 1991, segnitite was approved as a new mineral. Segnitite has since been found worldwide near similar locality types where rocks are rich in zinc and lead especially. it was named for Australian mineralogist, gemologist and petrologist Edgar Ralph Segnit. The mineral was named after E. R. Segnit due to his contributions to Australian mineralogy.

The phosphate sulfates are mixed anion compounds containing both phosphate and sulfate ions. Related compounds include the arsenate sulfates, phosphate selenates, and arsenate selenates.

References

  1. ↑ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi: 10.1180/mgm.2021.43 . S2CID   235729616.
  2. 1 2 3 4 5 6 7 8 9 10 Frost R. L., Duong L., Martens W. (2003) Molecular assembly in secondary minerals – Raman spectroscopy of the arthurite group species arthurite and whitmoreite. Neues Jahrbuch für Mineralogie, Monatshefte, 2003, 223–240.
  3. 1 2 3 4 5 6 Davis, R. J. & Hey, M. H. (1964) Arthurite, a new copper-iron arsenate from Cornwall. Mineralogical Magazine , 33, 937–941.
  4. ↑ Palmer, S.J., Frost R.L. (2011) The structure of the mineral arthurite CuFe23+(AsO4,PO4,SO4)2(O,OH)2·4H2O – A Raman spectroscopic study. Journal of Molecular Structure, 994, 283–288.
  5. 1 2 3 4 Clark, A. H. & Sillitoe, R. H. (1969) Arthurite from Potrerillos, Atacama Province, Chile. Mineralogical Magazine, 37, 519–520.
  6. ↑ Davis, R. J. & Hey, M. H. (1969) The cell-contents of arthurite redetermined. Mineralogical Magazine, 37, 520–521.
  7. ↑ Jambor, J.L., Viñals, Joan, Groat, Lee A., Raudsepp, Mati. (2002) Cobaltarthurite, Co2+Fe23+(AsO4,PO4,SO4)2(O,OH)2·4H2O, A New Member of the Arthurite Group. The Canadian Mineralogist, 40, 725–732.
  8. 1 2 Kolitsch, U., Atencio, D., Chukanov, N.V., Zubkova, N.V., Menezes Filho, L.A.D., Coutinho, J.M.V., Birch, W.D., Schlüter, J., Pohl, D., Kampf, A.R., Steele, I.M., Favreau, G., Nasdala, L., Möckel, S., Giester, G., Pushcharovsky, D.Yu. (2010) Bendadaite, a new iron arsenate mineral of the arthurite group. Mineralogical Magazine, 74, 469–486.
  9. 1 2 Raudsepp, Mati & Pani, Elisabetta. (2002) The Crystal Structure of Cobaltarthurite, Co2+Fe23+(AsO4,PO4,SO4)2(O,OH)2·4H2O: A Rietveld Refinement. The Canadian Mineralogist, 40, 733–737.
  10. ↑ Keller, P. & Hess, H. (1978) The crystal structure of arthurite, CuFe23+[(H2O)4|(OH)2|(AsO4)2]. Neues Jahrbuch für Mineralogie, Monatshefte und Abhandlungen, 133, 291–302.
  11. ↑ Embrey, P.G. (1973) Memorial of Arthur William Gerald Kingsbury. American Mineralogist, 58, 3–4, 372–375.
  12. ↑ Hart, A.D. & Symes, R.F. (1991) Arthur Edward Ian Montagu Russell. Journal of the Russell Society, 4, 1.
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