Duftite | |
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General | |
Category | Arsenate minerals |
Formula (repeating unit) | PbCuAsO4(OH) |
IMA symbol | Dft [1] |
Strunz classification | 8.BH.35 |
Dana classification | 41.5.1.4 |
Crystal system | Orthorhombic |
Crystal class | Disphenoidal (222) H-M symbol: (2 2 2) |
Space group | P212121 |
Unit cell | a = 7.768(1), b = 9.211(1) c = 5.999(1) [Å]; Z = 4 |
Identification | |
Formula mass | 426.67 g/mol |
Color | Green, olive green or grey green. Generally zoned due to compositional variations. |
Crystal habit | Tiny crystals elongated along [001] with curved and rough faces, aggregated into crusts. Crystals may be pseudo-octahedral. |
Cleavage | Indistinct |
Fracture | Uneven to conchoidal |
Mohs scale hardness | 4.5 |
Luster | Vitreous on fracture surfaces and dull on crystal faces |
Streak | Pale green or white |
Diaphaneity | Crystals are transparent to translucent |
Specific gravity | 6.4 (measured), 6.60 (calculated) |
Optical properties | Biaxial (-), faint apple-green color (transmitted light) |
Refractive index | nα = 2.03–2.04, nβ = 2.06–2.08, nγ = 2.08–2.10 |
Birefringence | δ = 0.06 |
2V angle | Large |
Dispersion | r > v, perceptible |
Solubility | Readily soluble in acids [2] |
Other characteristics | Decrepitates on heating. Not radioactive. |
References | [3] [4] [5] |
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. [6] It was named after Mining Councilor G Duft, Director of the Otavi Mine and Railroad Company, Tsumeb, Namibia. [2] The type locality is the Tsumeb Mine, Tsumeb, Otjikoto Region, Namibia.
The structure [7] is composed of chains of edge-sharing CuO6 distorted octahedra parallel to the c axis. The chains are linked by AsO4 tetrahedra and Pb atoms.
Duftite is an uncommon product of weathered sulfide ore deposits. It is associated with azurite at the type locality, [2] and with bayldonite, segnitite, agardite and gartrellite at the Central Cobar Mines, New South Wales, Australia, where some pseudomorphs of duftite after mimetite have also found. [8] It occurs in association with olivenite, mottramite, azurite, malachite, wulfenite and calcite in the Tsumeb, Namibia deposit. It occurs with bayldonite, beudantite, mimetite and cerussite in the Cap Garonne mine, France. [5]
Reported from Argentina, Australia, Austria, Chile, the Czech Republic, France, Germany, Greece, Italy, Japan, Mexico, Namibia, Poland, Portugal, Russia, South Africa, Spain, Switzerland, the UK, the US and Zimbabwe. [4]
Wulfenite is a lead molybdate mineral with the formula PbMoO4. It can be most often found as thin tabular crystals with a bright orange-red to yellow-orange color, sometimes brown, although the color can be highly variable. In its yellow form it is sometimes called "yellow lead ore".
Mimetite is a lead arsenate chloride mineral (Pb5(AsO4)3Cl) which forms as a secondary mineral in lead deposits, usually by the oxidation of galena and arsenopyrite. The name derives from the Greek Μιμητής mimetes, meaning "imitator" and refers to mimetite's resemblance to the mineral pyromorphite. This resemblance is not coincidental, as mimetite forms a mineral series with pyromorphite (Pb5(PO4)3Cl) and with vanadinite (Pb5(VO4)3Cl). Notable occurrences are Mapimi, Durango, Mexico and Tsumeb, Namibia.
Austinite is a member of the adelite-descloizite group, adelite subgroup, the zinc (Zn) end member of the copper-Zn series with conichalcite. It is the zinc analogue of cobaltaustinite and nickelaustinite. At one time “brickerite” was thought to be a different species, but it is now considered to be identical to austinite. Austinite is named in honour of Austin Flint Rogers (1877–1957), American mineralogist from Stanford University, California, US.
Vauquelinite is a complex mineral with the formula CuPb2(CrO4)(PO4)(OH) making it a combined chromate and phosphate of copper and lead. It forms a series with the arsenate mineral fornacite.
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.
Conichalcite, CaCu(AsO4)(OH), is a relatively common arsenate mineral related to duftite (PbCu(AsO4)(OH)). It is green, often botryoidal, and occurs in the oxidation zone of some metal deposits. It occurs with limonite, malachite, beudantite, adamite, cuproadamite, olivenite and smithsonite.
Ashburtonite is a rare lead copper silicate-bicarbonate mineral with formula: HPb4Cu2+4Si4O12(HCO3)4(OH)4Cl.
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 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 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.
Beudandite is a secondary mineral occurring in the oxidized zones of polymetallic deposits. It is a lead, iron, arsenate, sulfate with endmember formula: PbFe3(OH)6SO4AsO4.
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.
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 dolomite 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 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.
Hidalgoite, PbAl3(AsO4)(SO4)(OH)4, is a rare member of the beudantite group and is usually classified as part of the alunite family. It was named after the place where it was first discovered, the Zimapán mining district, Hidalgo, Mexico. At Hidalgo where it was initially discovered, it was found as dense white masses in alternating dikes of quartz latite and quartz monzonite alongside other secondary minerals such as sphalerite, arsenopyrite, cerussite and trace amounts of angelsite and alamosite, it was then rediscovered at other locations such as Australia where it occurs on oxidized shear zones above greywacke shales especially on the anticline prospects of the area, and on fine grained quartz-spessartine rocks in Broken Hill, Australia. Hidalgoite specimens are usually associated with copper minerals, clay minerals, iron oxides and polymetallic sulfides in occurrence.
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 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.
Minrecordite, CaZn(CO3)2, is a very rare mineral belonging to the dolomite group, the member with Ca and Zn. It was discovered, associated with dioptase, in a specimen from the Tsumeb mine (Namibia), which is consequently its type locality. Its name is a tribute to The Mineralogical Record magazine, representing the collaboration between professional and amateur mineralogists. In this locality it is associated primarily with dioptase, and less frequently with duftite, calcite and malachite. It is a rare mineral, which has been found only in a few deposits in the world. In addition to the type locality, it appears in the Preguiça mine, in Moura, district of Beja (Portugal).
Arsendescloizite is a lead-zinc mineral, approved by the IMA in 1982. It is an arsenate analog of descloizite. Its first description was published in 1982.
Gallobeudantite is a secondary, Gallium-bearing mineral of beudantite, where the Iron is replaced with Gallium, a rare-earth metal. It was first described as a distinct mineral by Jambor et al in 1996. Specific Gallium minerals are generally rare and Gallium itself is usually obtained as a by-product during the processing of the ores of other metals. In particular, the main source material for Gallium is bauxite, a key ore of aluminium. However, Gallobeudantite is too rare to be of economic value. Its main interest is academic and also among mineral collectors.
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