Plumbogummite

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Plumbogummite
Plumbogummite-pg10c.jpg
General
Category Phosphate minerals
Formula
(repeating unit)
PbAl3(PO4)2(OH)5·H2O
IMA symbol Pbg [1]
Strunz classification 8.BL.10
Dana classification42.7.3.5
Crystal system Trigonal
Crystal class Hexagonal scalenohedral (3m)
H-M symbol: (3 2/m)
Space group R3m
Identification
Formula mass 581.14 g/mol
ColorBlue, grey, greenish or yellow
Crystal habit Crystals, rare, have a hexagonal outline
Cleavage None
Fracture Uneven or sub-conchoidal
Tenacity Brittle
Mohs scale hardness4 to 5 [2] [3] or 4.5 to 5 [4] [5]
Luster Resinous or dull
Streak White
Diaphaneity Translucent
Specific gravity 4.014
Optical propertiesUniaxial (+), segments of crystals may be biaxial [5]
Refractive index no = 1.653 [4] or 1.653 to 1.688 [5]

ne = 1.675 [4] or 1.675 to 1.704 [5]

no = 1.722 and ne = 1.742 for Ga-rich plumbogummite [6]
Pleochroism None [6]
Solubility Soluble in hot acids
Other characteristicsNon-fluorescent, not radioactive
References [2] [3] [4] [5]

Plumbogummite is a rare secondary lead phosphate mineral, belonging to the alunite supergroup of minerals, crandallite subgroup. [2] Some other members of this subgroup are:

Contents

Plumbogummite was discovered in 1819 [2] and named in 1832 [4] from the Latin "plumbum" for lead, and "gummi" for gum, in allusion to its lead content and appearance, which at times resembles coatings of gum.

Unit cell

Plumbogummite crystallizes in space group R3m. The reported lattice parameters (the lengths of the sides of the unit cell) vary in detail according to the source, but all agree that normal plumbogummite has "a" close to 7 Å and "c" close to 17 Å, with Z=3. Various reported values of "a" and "c"are:

a = 7.01 Å, [2] 7.017 Å, [5] 7.018 Å, [3] 7.033 Å [4]
c = 16.71Å, [2] 16.75 Å, [5] 16.784 Å, [3] 16.789 Å [4]

Mills et al. [6] investigated a gallium-rich sample of plumbogummite from Tsumeb, Namibia, and found larger cell parameters, with a = 7.0752 Å and c = 16.818 Å.

Structure

The basic structural units of plumbogummite are PO4 tetrahedra, with phosphorus atoms (P) at the center and oxygen atoms (O) at the corners, together with AlO6 octahedra, aluminium atoms (Al) at the center and oxygen atoms at the corners. The tetrahedra and octahedra combine by sharing corners, to form composite layers. Lead atoms (Pb) occupy sites between the layers. [6]

Environment

Plumbogummite is found in the oxidized zones of lead-bearing deposits. It commonly occurs as botryoidal, kidney shaped, stalactitic or globular crusts or masses, frequently with a concentric structure; rare crystals have a hexagonal outline. Pyromorphite and baryte are commonly associated minerals, and plumbogummite may be pseudomorphic after them. Other associated minerals include mimetite, duftite, cerussite, anglesite and wulfenite. [5]

Occurrence

The type locality is Huelgoat, Finistère, Brittany, France, and the type material is stored in the Natural History Museum, Paris, France. [5]

Plumbogummite has been found in the Central Cobar Mines, New South Wales, Australia [7] and the Nifty Copper Mine, Western Australia. [8] Also in the Kintore open cut at Broken Hill, New South Wales, Australia, but it is generally inconspicuous there and only a few specimens have been collected. [9]

Material from the Siglio XX Mine, Llallagua, Bolivia, is an unusual pale yellow color, rather than the more common blue or green, forming crusts on quartz and cassiterite, and enclosing crude octahedral jeanbandyite crystals with orange colored shells of plumbogummite. [10]

Related Research Articles

<span class="mw-page-title-main">Mineral</span> Crystalline chemical element or compound formed by geologic processes

In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.

<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">Brazilianite</span>

Brazilianite, whose name derives from its country of origin, Brazil, is a typically yellow-green phosphate mineral, most commonly found in phosphate-rich pegmatites.

<span class="mw-page-title-main">Silicate mineral</span> Rock-forming minerals with predominantly silicate anions

Silicate minerals are rock-forming minerals made up of silicate groups. They are the largest and most important class of minerals and make up approximately 90 percent of Earth's crust.

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

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.

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

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

Bergenite is a rare uranyl phosphate of the more specific phosphuranylite group. The phosphuranylite-type sheet in bergenite is a new isomer of the group, with the uranyl phosphate tetrahedra varying in an up-up-down, same-same-opposite (uuduudSSOSSO) orientation. All bergenite samples have been found in old mine dump sites. Uranyl minerals are a large constituent of uranium deposits.

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

Cyrilovite (NaFe33+(PO4)2(OH)4·2(H2O)) is a hydrous sodium iron phosphate mineral. It is isomorphous and isostructural with wardite, the sodium aluminium counterpart.

<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.

This list gives an overview of the classification of non-silicate minerals 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, not IMA approved minerals, not named minerals are mostly excluded. Mostly major groups only, or groupings used by New Dana Classification and Mindat.

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

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.

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

Perhamite is a phosphate mineral with the formula Ca3Al7(SiO4)3(PO4)4(OH)3·16.5(H2O). It occurs in rare isolated masses in amblygonite-rich pegmatite deposits throughout the world. It was discovered in platy sheed form of 1mm hexagonal crystals. It was first described in 1977 by P.J. Dunn and D.E. Appleman from pegmatite collected from Bell Pit, Newry, Maine. Other specimens have been found in Kapunda, South Australia, in Silver Coin mine near Humboldt County, Nevada and various locations throughout Europe.

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

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.

<span class="mw-page-title-main">Hidalgoite</span> Mineral of the beudantite group

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.

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.

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

Zigrasite is a phosphate mineral with the chemical formula of MgZr(PO4)2(H2O)4. Zigrasite was discovered and is only known to occur in the Dunton Quarry at Oxford County, Maine. Zigrasite was specifically found in the giant 1972 gem tourmaline-bearing pocket at the Dunton Quarry. Zigrasite is named after James Zigras who originally discovered and brought the mineral to attention.

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

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.

Cattiite is a phosphate mineral. The mineral was first found in a veins of dolomite carbonatites veins at the bottom of the Zhelezny (Iron) Mine in the Kovdor massif, Kola Peninsula, Russia. Cattiite was tentatively identified as Mg3(PO4)2•22H2O, which as a high hydrate magnesium orthophosphate. Later structural studies, revealed the existence of two polytypes named Mg3(PO4)2•22H2O-1A1 and Mg3(PO4)2•22H2O-1A2.

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 Mindat.org
  3. 1 2 3 4 Webmineral data
  4. 1 2 3 4 5 6 7 Gaines et al (1997) Dana's New Mineralogy Eighth Edition, Wiley
  5. 1 2 3 4 5 6 7 8 9 Handbook of Mineralogy
  6. 1 2 3 4 Mineralogical Magazine (2009) 73(5), 837–845
  7. Australian Journal of Mineralogy 11-2, 77
  8. Australian Journal of Mineralogy 12-1, 28
  9. Australian Journal of Mineralogy 3-1, 32 and 50
  10. Mineralogical Record 37-2, 127 and 148