Smithsonite

Smithsonite, or zinc spar, is zinc carbonate (ZnCO3), a mineral ore of zinc. Historically, smithsonite was identified with hemimorphite before it was realised that they were two distinct minerals. The two minerals are very similar in appearance and the term calamine has been used for both, leading to some confusion. The distinct mineral smithsonite was named in 1832 by François Sulpice Beudant in honor of English chemist and mineralogist James Smithson (c.1765–1829), whose bequest established the Smithsonian Institution and who first identified the mineral in 1802.[2][4]

Smithsonite is a variably colored trigonal mineral which only rarely is found in well formed crystals. The typical habit is as earthy botryoidal masses. It has a Mohs hardness of 4.5 and a specific gravity of 4.4 to 4.5.

Smithsonite occurs as a secondary mineral in the weathering or oxidation zone of zinc-bearing ore deposits. It sometimes occurs as replacement bodies in carbonate rocks and as such may constitute zinc ore. It commonly occurs in association with hemimorphite, willemite, hydrozincite, cerussite, malachite, azurite, aurichalcite and anglesite. It forms two limited solid solution series, with substitution of manganese leading to rhodochrosite, and with iron, leading to siderite.[3]

Smithsonite
Smithsonite-Willemite-cktsu-23a
General
CategoryCarbonate mineral
Formula
(repeating unit)
ZnCO3
Strunz classification5.AB.05
Crystal systemTrigonal
Crystal classHexagonal scalenohedral (3m)
H-M symbol: (3 2/m)
Space groupR3c
Unit cella = 4.6526(7)
c = 15.0257(22) [Å]; Z = 6
Identification
ColorWhite, grey, yellow, green to apple-green, blue, pink, purple, bluish grey, and brown
Crystal habitUncommon as crystals, typically botryoidal, reniform, spherulitic; stalactitic, earthy, compact massive
TwinningNone observed
CleavagePerfect on [1011]
FractureUneven, sub-conchoidal
TenacityBrittle
Mohs scale hardness4.5
LusterVitreous, may be pearly
StreakWhite
DiaphaneityTranslucent
Specific gravity4.4 - 4.5
Optical propertiesUniaxial (-)
Refractive indexnω = 1.842 - 1.850 nε = 1.619 - 1.623
Birefringenceδ = 0.223 - 0.227
Ultraviolet fluorescenceMay fluoresce pale green or pale blue under UV
References[1][2][3]

Gallery

Smithsonite 4

Crystals of smithsonite: Ojuela Mine, Mapimi, Mun. de Mapimi, Durango, Mexico

Smithsonite-52236

Crystals of pink Cobaltoan smithsonite on matrix

Smithsonite-279094

Apple-green Cuprian smithsonite crystals. A second generation of drusy smithsonite was deposited in the crevasses between the larger growth

Smithsonite-139792

Crystals of slightly pink cobaltoan smithsonite, Tsumeb, 6.8 x 4.6 x 3.7 cm

Smithsonite Kelly Mine

Blue smithsonite from the Kelly Mine in New Mexico

See also

Bibliography

  • Tom Hughes, Suzanne Liebetrau, and Gloria Staebler, eds. (2010). Smithsonite: Think Zinc! Denver, CO: Lithographie ISBN 978-0-9790998-6-1.
  • Ewing, Heather (2007). The Lost World of James Smithson: Science, Revolution, and the Birth of the Smithsonian. London and New York: Bloomsbury ISBN 978-1-59691-029-4

References

  1. ^ Smithsonite: Smithsonite mineral information and data from Mindat
  2. ^ a b Smithsonite mineral data from Webmineral
  3. ^ a b Handbook of mineralogy
  4. ^ "Smithsonite at the National Museum of Natural History". Smithsonian Institution. Retrieved 8 December 2010.

External links

Aurichalcite

Aurichalcite is a carbonate mineral, usually found as a secondary mineral in copper and zinc deposits. Its chemical formula is (Zn,Cu)5(CO3)2(OH)6. The zinc to copper ratio is about 5:4.

Botryoidal

A botryoidal texture or mineral habit is one in which the mineral has a globular external form resembling a bunch of grapes (botrys in ancient Greek). This is a common form for many minerals, particularly hematite, the classically recognized shape. It is also a common form of goethite, smithsonite, fluorite and malachite. This includes chrysocolla.

Each sphere (grape) in a botryoidal mineral is smaller than that of a reniform mineral, and much smaller than that of a mamillary mineral. Botryoidal minerals form when many nearby nuclei, specks of sand, dust, or other particles, are present. Acicular or fibrous crystals grow radially around the nuclei at the same rate, appearing as spheres. Eventually, these spheres abut or overlap with those that are nearby. These nearby spheres are then fused together to form the botryoidal cluster.

Bromargyrite

Bromyrite or bromargyrite is a natural mineral form of silver bromide found mainly in Mexico and Chile. Hardness is 1.5 to 2. Related are chlorargyrite and iodyrite.

It was first described in 1859 for an occurrence in Plateros, Zacatecas, Mexico where it occurred in a silver deposit as an oxidation product of primary ore minerals. It occurs in arid environments along with native silver, iodargyrite and smithsonite along with iron and manganese oxide minerals.

Calamine (mineral)

Calamine is a historic name for an ore of zinc. The name calamine was derived from lapis calaminaris, a Latin corruption of Greek cadmia (καδμία), the old name for zinc ores in general. The name of the Belgian town of Kelmis, La Calamine in French, which was home to a zinc mine, comes from this. In the 18th and 19th centuries large ore mines could be found near the German village of Breinigerberg.

During the early 19th century it was discovered that what had been thought to be one ore was actually two distinct minerals:

Zinc carbonate ZnCO3 or smithsonite and

Zinc silicate Zn4Si2O7(OH)2·H2O or hemimorphite.Although chemically and crystallographically quite distinct, the two minerals exhibit similar massive or botryoidal external form and are not readily distinguished without detailed chemical or physical analysis. The first person to separate the minerals was the British chemist and mineralogist James Smithson in 1803. In the mining industry the term calamine has been historically used to refer to both minerals indiscriminately.

In mineralogy calamine is no longer considered a valid term. It has been replaced by smithsonite and hemimorphite in order to distinguish it from the pinkish mixture of zinc oxide (ZnO) and iron(III) oxide (Fe2O3) used in calamine lotion.

Carbonate minerals

Carbonate minerals are those minerals containing the carbonate ion, CO32−.

Coat of arms of Bytom

The coat of arms of Bytom in Silesia, Poland, was adopted in 1886 by a resolution of the town council.

The arms are composed of two symbols. The left (heraldic: dexter) half shows a miner digging with a pickaxe for smithsonite, referring to the town's centuries-long tradition as a mining area. The right (heraldic: sinister) half features a golden demi-eagle on a blue field, (half of) the device of the Upper Silesian dukes of the Piast dynasty. This combination of a miner and the ducal eagle dates from the 14th century.

Conichalcite

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.

Fraipontite

Fraipontite is a zinc aluminium silicate mineral with a formula of (Zn,Al)3(Si,Al)2O5(OH)4.It is a member of the kaolinite-serpentine mineral group and occurs as an oxidation product of zinc deposits. It occurs with smithsonite, gebhardite, willemite, cerussite and sauconite.It was first described in 1927 for an occurrence in Vieille Montagne, Verviers, Liège Province, Belgium. It was named for Julien Jean Joseph de Fraipont (1857–1910), and Charles de Fraipont, geologists of Liege, Belgium. In addition to the type locality in Belgium, it has been reported from Tsumeb, Namibia; Laurium, Greece; Swaledale, North Yorkshire, England; the Silver Bill mine, Cochise County, Arizona, the Blanchard Mine, Socorro County, New Mexico and the Mohawk mine, San Bernardino County, California in the US; and from the Ojuela mine, Mapimi, Durango, Mexico.A synonym of the fraipontite is the zinalsite, which was reported in 1956 for an occurrence in Kazakhstan.

Hemimorphite

Hemimorphite, is Zn4(Si2O7)(OH)2·H2O, a component of calamine. It is a sorosilicate mineral which has been historically mined from the upper parts of zinc and lead ores, chiefly associated with smithsonite, ZnCO3. They were assumed to be the same mineral and both were classed under the same name of calamine. In the second half of the 18th century it was discovered that these two different minerals were both present in calamine. They closely resemble each other.

The silicate was the rarer of the two, and was named hemimorphite, because of the hemimorph development of its crystals. This unusual form, which is typical of only a few minerals, means that the crystals are terminated by dissimilar faces. Hemimorphite most commonly forms crystalline crusts and layers, also massive, granular, rounded and reniform aggregates, concentrically striated, or finely needle-shaped, fibrous or stalactitic, and rarely fan-shaped clusters of crystals.

Some specimens show strong green fluorescence in shortwave ultraviolet light (253.7 nm) and weak light pink fluorescence in longwave UV.

Hydrozincite

Hydrozincite, also known as zinc bloom or marionite, is a white carbonate mineral consisting of Zn5(CO3)2(OH)6. It is usually found in massive rather than crystalline form.

It occurs as an oxidation product of zinc ores and as post mine incrustations. It occurs associated with smithsonite, hemimorphite, willemite, cerussite, aurichalcite, calcite and limonite.It was first described in 1853 for an occurrence in Bad Bleiberg, Carinthia, Austria and named for its chemical content.

James Smithson

James Smithson, MA, FRS (c. 1765 – 27 June 1829) was an English chemist and mineralogist. He published numerous scientific papers for the Royal Society during the late 1700s as well as assisting in the development of calamine, which would eventually be renamed after him as "smithsonite". He was the founding donor of the Smithsonian Institution, which also bears his name.

Born in Paris, France as the illegitimate child of Hugh Percy, the 1st Duke of Northumberland, he was given the French name Jacques-Louis Macie. His birth date was not recorded and the exact location of his birth is unknown; most sources believe it to be in the Pentemont Abbey. Shortly after his birth he naturalized to Britain where his name was anglicized to James Louis Macie. He attended university at Pembroke College, Oxford in 1782 eventually graduating with a B.A. in 1786. As a student he participated in numerous geological expeditions and studied chemistry and mineralogy. At the age of twenty-two, he adopted his father's surname of Smithson and travelled extensively throughout Europe, publishing papers about his findings. Considered a talented amateur in his field, Smithson maintained an inheritance he acquired from his mother and other relatives.Smithson never married and had no children; therefore, when he wrote his will, he left his estate to his nephew, or his nephew's family if his nephew died before Smithson. If his nephew were to die without heirs, however, Smithson's will stipulated that his estate be used "to found in Washington, under the name of the Smithsonian Institution, an establishment for the increase and diffusion of knowledge among men." In 1835, his nephew died and so could not claim to be the recipient of his estate; therefore, Smithson became the patron of the Smithsonian Institution in Washington, D.C. despite having never visited the United States. He died in Genoa, Italy on 27 June 1829, aged 64.

Legrandite

Legrandite is a rare zinc arsenate mineral, Zn2(AsO4)(OH)·(H2O).

It is an uncommon secondary mineral in the oxidized zone of arsenic bearing zinc deposits and occurs rarely in granite pegmatite. Associated minerals include: adamite, paradamite, köttigite, scorodite, smithsonite, leiteite, renierite, pharmacosiderite, aurichalcite, siderite, goethite and pyrite. It has been reported from Tsumeb, Namibia; the Ojuela mine in Durango, Mexico and at Sterling Hill, New Jersey, US.It was first described in 1934 for an occurrence in the Flor de Peña Mine, Nuevo León, Mexico and named after M. Legrand, a Belgian mining engineer .

Mount Sherman

Mount Sherman is a high mountain summit in the Mosquito Range of the Rocky Mountains of North America. The 14,043-foot (4,280 m) fourteener is located 6.8 miles (11.0 km) east by south (bearing 103°) of the City of Leadville, Colorado, United States, on the drainage divide separating San Isabel National Forest and Lake County from Pike National Forest and Park County. The mountain was named in honor of General William Tecumseh Sherman.

Otavite

Otavite is a rare cadmium carbonate mineral with the formula CdCO3. Otavite crystallizes in the trigonal system and forms encrustations and small scalenohedral crystals that have a pearly to adamantine luster. The color is white to reddish to yellow brown. Its Mohs hardness is 3.5 to 4 and the specific gravity is 5.04. Associated minerals include azurite, calcite, malachite, and smithsonite.

It was first described in 1906 from the Tsumeb district near Otavi, Namibia.

Rush Creek mining district

The best known and most prolific zinc mining region of north Arkansas for many years was the Rush Creek mining district of Marion County. Its history began when John Wolfer—an early prospector along the Buffalo River—discovered a large deposit of zinc on the creek in southern Marion County. George Chase purchased Wolfer's claim and established the Morning Star Mining Company, which eventually became one of the largest producers of zinc in Arkansas. One day a miner at the Morning Star Mine extracted a single mass of pure smithsonite (zinc carbonate) weighing 12,750 pounds.The miners originally thought that they were mining silver. They soon discovered that the "silver" that they were mining was not actually silver; it was zinc. Two to five thousand people lived in Rush Creek during the boom period, during World War I.Individual mines of the Rush District included:

Climax Mine

Mattie May Mine

Monte Cristo mine ("Monte Christo" mine)

Philadelphia mine

Silver Hollow MineRush was a true influence to North Arkansas and the Buffalo River Valley.

Sauconite

Sauconite is a complex phyllosilicate mineral of the smectite clay group, formula Na0.3Zn3(SiAl)4O10(OH)2·4H2O. It forms soft earthy bluish white to red-brown monoclinic crystals typically massive to micaceous in habit. It has a Mohs hardness of 1 to 2 and a specific gravity of 2.45. Optically it is biaxial positive with refractive index values of nα = 1.550 - 1.580, nβ = 1.590 - 1.620 and nγ = 1.590 - 1.620.

It is found in vugs and seams in the oxidized zones of zinc and copper deposits. It occurs in association with hemimorphite, smithsonite, chrysocolla, coronadite and various iron oxides.

It was named for the Saucon Valley in Pennsylvania, where it was originally discovered in 1875.

Siderite

Siderite is also the name of a type of iron meteorite.Siderite is a mineral composed of iron(II) carbonate (FeCO3). It takes its name from the Greek word σίδηρος sideros, “iron”. It is a valuable iron mineral, since it is 48% iron and contains no sulfur or phosphorus. Zinc, magnesium and manganese commonly substitute for the iron resulting in the siderite-smithsonite, siderite-magnesite and siderite-rhodochrosite solid solution series.Siderite has Mohs hardness of 3.75-4.25, a specific gravity of 3.96, a white streak and a vitreous lustre or pearly luster. Siderite is antiferromagnetic below its Néel temperature of 37 K which can assist in its identification.It crystallizes in the trigonal crystal system, and are rhombohedral in shape, typically with curved and striated faces. It also occurs in masses. Color ranges from yellow to dark brown or black, the latter being due to the presence of manganese.

Siderite is commonly found in hydrothermal veins, and is associated with barite, fluorite, galena, and others. It is also a common diagenetic mineral in shales and sandstones, where it sometimes forms concretions, which can encase three-dimensionally preserved fossils. In sedimentary rocks, siderite commonly forms at shallow burial depths and its elemental composition is often related to the depositional environment of the enclosing sediments. In addition, a number of recent studies have used the oxygen isotopic composition of sphaerosiderite (a type associated with soils) as a proxy for the isotopic composition of meteoric water shortly after deposition.

Skorpion Zinc

Skorpion Zinc is a zinc mine in the ǁKaras Region of southern Namibia, producing Special High Grade (SHG) zinc. The mine is situated near Rosh Pinah and opened in 2001. It is the eighth-largest zinc mine in the world, and the largest employer of Rosh Pinah, providing 1,900 jobs.Skorpion is a unique mine in several ways. Firstly, it is a supergene zinc ore body composed of alluvial accumulations of zinc carbonate and silicate minerals of detrital nature deposited within a palaeochannel. There are no other currently commercially viable deposits of this type. It is also one of the few mines in the world which mines "zinc oxides", which actually is a mixture of non sulphidic zinc minerals such as smithsonite, hydrozincite, tarbuttite and willemite. Finally, it is the only zinc processing facility to use solvent extraction-electrowinning metallurgy to process and refine its zinc products (others using conventional smelting and roasting).

The Skorpion SX-EW plant creates Special High Grade, ultra-pure zinc cathode as a primary product, which is so low in impurities that it commands a price premium.

Since November 2010 it is owned and operated by Vedanta Resources.

Supergene (geology)

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 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 Cu1.8S, and djurleite Cu31S16 are deposited by the descending surface waters.All such processes take place at essentially atmospheric conditions, 25 °C and atmospheric pressure.

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