Tsumebite

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Tsumebite
Tsumebite-278446.jpg
Tsumebite from the Bluebell Claims, California, US.
General
Category Phosphate minerals
Formula
(repeating unit)
Pb2Cu(PO4)(SO4)(OH)
IMA symbol Tsu [1]
Strunz classification 8.BG.05
Dana classification43.4.2.1
Crystal system Monoclinic
Crystal class Prismatic (2/m)
(same H-M symbol)
Space group P21/m
Identification
Formula mass 685.99 g/mol
ColorEmerald-green, green in transmitted light
Crystal habit Crusts of intergrown crystals on matrix
Twinning Almost always twinned. Twins may be multiple, with serrated re-entrants.
Cleavage None
Fracture Uneven
Tenacity Brittle
Mohs scale hardness3+12
Luster Adamantine to vitreous
Streak Green
Diaphaneity Transparent
Specific gravity 6.13
Optical propertiesBiaxial (+)
Refractive index Nx = 1.885 to 1.900, Ny = 1.920, Nz = 1.942 to 1.956
Pleochroism Faint: X = Y = very pale blue to colorless; Z = robin’s-egg-blue [2] [3]
Solubility Readily soluble in HCl and slowly soluble in HNO3. [4]
References [2] [4] [5] [6]

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.

Contents

The brackebuschite group

The minerals in the brackebuschite group have the general formula A2B(H2O,OH)(TO4)2 and crystallise in the monoclinic system, space group P21/m. The group includes: [5]

Structure

The structure of the brackebuschite group minerals is composed of B-(O,OH)6 octahedra, two non-equivalent TO4 tetrahedra, TO4(1) and TO4(2), and two different irregular polyhedra of large cations. B and T represent different elements in different members of the group. Chains formed from the B octahedra link through the oxygens of TO4(2) tetrahedra, while the large cation polyhedra form double chains parallel to the b crystal axis through edge sharing with TO4(1) tetrahedra. The result is a tight three-dimensional structure. [5] In tsumebite copper ions occupy the B sites, and phosphorus and sulfur occupy the T sites. Lead is the large cation.

Unit cell

Tsumebite belongs to the monoclinic crystal class 2/m, meaning that it has one twofold axis of symmetry perpendicular to a mirror plane. The space group is P 21/m, meaning that the crystal lattice is a primitive lattice, with structural elements only at the vertices of the unit cell. These structural elements are made up of two formula units (Z = 2).
Unit cell parameters are a = 8.69 Å, b = 5.78 Å, c = 7.86 Å, β = 111.87° [4] [5] [6] or a = 8.70 Å, b = 5.80 Å, c = 7.85 Å, β = 111.5°. [2] [3]

Optical properties

Tsumebite is an emerald-green color, transparent and green in transmitted light, with a green streak and an adamantine (diamond-like) to vitreous (glassy) luster. It is biaxial (+) with refractive indices Nx = 1.885 to 1.900, Ny = 1.920 and Nz = 1.942 to 1.956. It is faintly pleochroic with X = Y = very pale blue to colorless and Z = robin's-egg-blue. [2] [3]

Physical properties

The mineral typically occurs as crusts of intergrown crystals on matrix. Cleavage is absent, but twinning is almost universal, and twins may be multiple, with serrated re-entrants. [2] It is brittle, with an uneven fracture, hardness 3+12 and specific gravity 6.13. It is readily soluble in hydrochloric acid HCl and slowly soluble in nitric acid HNO3. [4] It is not radioactive. [6]

Environment

Tsumebite is a rare secondary mineral in the oxidised zone of some arsenic-bearing lead-copper deposits, with other lead-bearing phosphates and sulfates. [2] Associated minerals include azurite, smithsonite, malachite, cerussite, mimetite, wulfenite and olivenite. [2] The type locality is the Tsumeb mine, Tsumeb, Otjikoto Region, Namibia. [4] The Handbook of Mineralogy [2] states that the type material was destroyed by bombing, but does not indicate when or where.

Tsumebite occurs at Morenci, Arizona, predominantly as twinned crystals associated with wulfenite, olivenite and the hyalite variety of opal. [3] At Broken Hill, New South Wales, Australia, tsumebite has been found as lustrous pale blue to bluish green crystals. It usually occurs with yellow crusts of corkite-hinsdalite, colorless to white pyromorphite needles and sprays of pale greyish green zincian libethenite. Less commonly found with scholzite and torbernite. [7]

Related Research Articles

Olivenite

Olivenite is a copper arsenate mineral, formula Cu2AsO4OH. It crystallizes in the monoclinic system (pseudo-orthorhombic), and is sometimes found in small brilliant crystals of simple prismatic habit terminated by domal faces. More commonly, it occurs as globular aggregates of acicular crystals, these fibrous forms often having a velvety luster; sometimes it is lamellar in structure, or soft and earthy.

Liroconite Copper aluminium arsenate mineral

Liroconite is a complex mineral: Hydrated copper aluminium arsenate hydroxide, with the formula Cu2Al[(OH)4|AsO4]·4(H2O). It is a vitreous monoclinic mineral, colored bright blue to green, often associated with malachite, azurite, olivenite, and clinoclase. It is quite soft, with a Mohs hardness of 2 - 2.5, and has a specific gravity of 2.9 - 3.0.

Vauxite

Vauxite is a phosphate mineral with the chemical formula Fe2+Al2(PO4)2(OH)2·6(H2O). It belongs to the laueite – paravauxite group, paravauxite subgroup, although Mindat puts it as a member of the vantasselite Al4(PO4)3(OH)3·9H2O group. There is no similarity in structure between vauxite and paravauxite Fe2+Al2(PO4)2(OH)2·8H2O or metavauxite Fe3+Al2(PO4)2(OH)2·8H2O, even though they are closely similar chemically, and all minerals occur together as secondary minerals. Vauxite was named in 1922 for George Vaux Junior (1863–1927), an American attorney and mineral collector.

Fornacite

Fornacite is a rare lead, copper chromate arsenate hydroxide mineral with the formula: Pb2Cu(CrO4)(AsO4)(OH). It forms a series with the phosphate mineral vauquelinite. It forms variably green to yellow, translucent to transparent crystals in the monoclinic - prismatic crystal system. It has a Mohs hardness of 2.3 and a specific gravity of 6.27.

Duftite Arsenate mineral

Duftite is a relatively common arsenate mineral with the formula CuPb(AsO4)(OH), related to conichalcite. It is green and often forms botryoidal aggregates. It is a member of the adelite-descloizite Group, Conichalcite-Duftite Series. Duftite and conichalcite specimens from Tsumeb are commonly zoned in color and composition. Microprobe analyses and X-ray powder-diffraction studies indicate extensive substitution of Zn for Cu, and Ca for Pb in the duftite structure. This indicates a solid solution among conichalcite, CaCu(AsO4 )(OH), austinite, CaZn(AsO4)(OH) and duftite PbCu(AsO4)(OH), all of them belonging to the adelite group of arsenates. It was named after Mining Councilor G Duft, Director of the Otavi Mine and Railroad Company, Tsumeb, Namibia. The type locality is the Tsumeb Mine, Tsumeb, Otjikoto Region, Namibia.

Plumbogummite Alunite supergroup, phosphate mineral

Plumbogummite is a rare secondary lead phosphate mineral, belonging to the alunite supergroup of minerals, crandallite subgroup. Some other members of this subgroup are:

Lavendulan

Lavendulan is an uncommon copper arsenate mineral, known for its characteristic intense electric blue colour. It belongs to the lavendulan group, which has four members:

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.

Warikahnite

Warikahnite is a rare zinc arsenate mineral of the triclinic crystal system with Hermann- Mauguin notation 1, belonging to the space group P1. It occurs in the Tsumeb mine in Namibia on corroded tennantite in the second oxidation zone under hydrothermal conditions in a dolomite-hosted polymetallic ore deposit. It is associated with adamite, stranskiite, koritnigite, claudetite, tsumcorite, and ludlockite. The origin of discovery was in a dolosmite ore formation within an oxidized hydrothermal zone, in the E9 pillar, 31st level of the Tsumeb Mine in Namibia, Southwest Africa. It has also been found at Lavrion, Greece and Plaka, Greece as microscopic white needles.

Tsumcorite

Tsumcorite is a rare hydrated lead arsenate mineral that was discovered in 1971, and reported by Geier, Kautz and Muller. It was named after the TSUMeb CORporation mine at Tsumeb, in Namibia, in recognition of the Corporation's support for mineralogical investigations of the orebody at its Mineral Research Laboratory.

Satterlyite

Satterlyite is a hydroxyl bearing iron phosphate mineral. The mineral can be found in phosphatic shales and was first discovered in the Big Fish River area in Yukon Territory, Canada.

Penikisite was discovered by Alan Kulan and Gunar Penikis near Rapid Creek, Yukon Territory. The mineral is a member of the bjarebyite group along with kulanite, ideally BaFe2+2Al2(PO4)3(OH)3, and bjarebyite, ideally BaMn2+2Al2(PO4)3(OH)3. It is among several new minerals that have been discovered in the Rapid Creek and Big Fish areas of Yukon Territory. Kulanite is similar in many ways to penikisite in appearance and properties. The chemical formula for penikisite is Ba(Mg,Fe,Ca)Al2(PO4)2(OH)3. It has a hardness of about 4 and a density of 3.79 g/cm3. Penikisite is unique among the bjarebyite group in being monoclinic and has a biaxial optical class. It comes in shades of blue and green and, when rubbed on a streak plate, is pale green to white in color. Although penikisite and kulanite both range from blue to green, penikisite zones are easily distinguishable from kulanite zones in kulanite-penikisite crystals because they are lighter than the darker kulanite in color. Penikisite is a phosphate and is different from kulanite in that it is a magnesium-rich phosphate whereas kulanite is an iron-rich phosphate.

Ianbruceite

Ianbruceite is a rare hydrated zinc arsenate with the formula [Zn2(OH)(H2O)(AsO4)](H2O)2; material from the Driggith mine has traces of cobalt. It was first discovered at Tsumeb, approved by the International Mineralogical Association as a new mineral species in 2011, reference IMA2011-49, and named for Ian Bruce, who founded "Crystal Classics" in the early 1990s, and was heavily involved in attempts to reopen the famous Tsumeb mine for specimen mining.
In 2013 new occurrences of ianbruceite were reported from the neighbouring Driggith and Potts Gill mines on High Pike in the Caldbeck Fells, Cumbria, England. Here the mineral is probably a post-mining product. Caldbeck Fells and Tsumeb are the only reported localities for ianbruceite to date (May 2013).

Carminite

Carminite (PbFe3+2(AsO4)2(OH)2) is an anhydrous arsenate mineral containing hydroxyl. It is a rare secondary mineral that is structurally related to palermoite (Li2SrAl4(PO4)4(OH)4). Sewardite (CaFe3+2(AsO4)2(OH)2) is an analogue of carminite, with calcium in sewardite in place of the lead in carminite. Mawbyite is a dimorph (same formula, different structure) of carminite; mawbyite is monoclinic and carminite is orthorhombic. It has a molar mass of 639.87 g. It was discovered in 1850 and named for the characteristic carmine colour.

Mottramite

Mottramite is an orthorhombic anhydrous vanadate hydroxide mineral, PbCu(VO4)(OH), at the copper end of the descloizite subgroup. It was formerly called cuprodescloizite or psittacinite (this mineral characterized in 1868 by Frederick Augustus Genth). Duhamelite is a calcium- and bismuth-bearing variety of mottramite, typically with acicular habit.

Falsterite is a rare phosphate mineral with the formula Ca2MgMn2+2(Fe2+0.5Fe3+0.5)4Zn4(PO4)8(OH)4(H2O)14. It is a pegmatitic mineral, related to the currently approved mineral ferraioloite.

Mammothite

Mammothite is a mineral found in the Mammoth mine in Tiger, Arizona and also in Laurium, Attika, Greece. This mineral was named in 1985 by Donald R. Peacor, Pete J. Dunn, G. Schnorrer-Köhler, and Richard A. Bideaux, for the Mammoth vein (one of the two main veins in the mine) and the town of Mammoth, Arizona, which was named for the mine. The mammothite that is found in Arizona exist as euhedral crystals imbedded in micro granular, white colored anglesite with a saccharoidal texture. The associated minerals include phosgenite, wulfenite, leadhillite and caledonite. In Greece, the mammothite exists as small euhedral crystals and also as microscopic rock cavities lined with projecting crystals within the slags. The associated minerals here are cerussite, phosgenite and matlockite. The ideal chemical formula for mammothite is Pb6Cu4AlSb5+O2(OH)16Cl4(SO4)2.

Lemanskiite is a mineral that was first discovered in a mine at Abundancia mine, El Guanaco mining district, Chile, with the ideal formula of NaCaCu5(AsO4)4Cl•3H2O. Originally, this mineral was discovered as being dimorphus with lavendulan, but in 2018 it was revised to only have 3 water molecules. Lemanskiite typically occurs as rosette-shaped aggregates of thin lamellar or needle-shaped aggregates, such as lammerite. Lemanskiite is dark sky blue with a light blue streak, it is brittle with an excellent cleavage plane. It was found on a dumping site in the abandoned Abundancia mine, El Guanaco mining district, Region II, Antofagasta Province, Chile The new mineral has been named after Chester S. Lemanski, Jr. This mineral and name were then approved by the Commission on New Minerals and Mineral Names of the International Mineralogical Association.

Serrabrancaite

Serrabrancaite is a mineral with the chemical formula MnPO4•H2O and which is named for the locality where it was found, the Alto Serra Branca Pegmatite. The Alto Serra Branca mine has been in operation since the 1940s. It is located in Paraiba, Brazil near a village named Pedra Lavrada. Tantalite is the main mineral mined here. Specimens of serrabrancaite are kept in the Mineralogical Collections of both the Bergakademie Freiberg, Germany and the Martin-Luther Universität Halle, Institut für Geologische Wissenschaften.

Rockbridgeite is an anhydrous phosphate mineral in the "Rockbridgeite" supergroup with the chemical formula Fe2+Fe3+4(PO4)3(OH)5. It was discovered at the since-shut-down Midvale Mine in Rockbridge County, Virginia, United States. The researcher who first identified it, Clifford Frondel, named it in 1949 for its region of discovery, Rockbridge County.

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 Handbook of Mineralogy
  3. 1 2 3 4 American Mineralogist (1966) 51: 258–259 and 267
  4. 1 2 3 4 5 Mindat.org
  5. 1 2 3 4 Gaines et al (1997) Dana’s New Mineralogy Eighth Edition, Wiley
  6. 1 2 3 Webmineral data
  7. Australian Journal of Mineralogy (1997) 3-1:53