Sphalerite
Template:Short description Template:Redirect Template:Use American English Template:Infobox mineral
Sphalerite is a sulfide mineral with the chemical formula Template:Chem2.<ref name="Muntyan-1999">Template:Cite journal</ref> It is the most important ore of zinc. Sphalerite is found in a variety of deposit types, but it is primarily in sedimentary exhalative, Mississippi-Valley type, and volcanogenic massive sulfide deposits. It is found in association with galena, chalcopyrite, pyrite (and other sulfides), calcite, dolomite, quartz, rhodochrosite, and fluorite.<ref name="Nesse-2013">Template:Cite book</ref>
German geologist Ernst Friedrich Glocker discovered sphalerite in 1847, naming it based on the Greek word sphaleros, meaning "deceiving", due to the difficulty of identifying the mineral.<ref>Template:Cite book</ref>
In addition to zinc, sphalerite is an ore of cadmium, gallium, germanium, and indium. Miners have been known to refer to sphalerite as zinc blende, black-jack, and ruby blende.<ref name="Rennie-Law-2016">Template:Cite book</ref> Marmatite is an opaque black variety with a high iron content.<ref>Template:Cite journal</ref>
Crystal habit and structureEdit
Sphalerite crystallizes in the face-centered cubic zincblende crystal structure,<ref name="Klein-2017a">Template:Cite book</ref> which was named after the mineral. This structure is a member of the hextetrahedral crystal class (space group FTemplate:Overline3m). In the crystal structure, both the sulfur and the zinc or iron ions occupy the points of a face-centered cubic lattice, with the two lattices displaced from each other such that the zinc and iron are tetrahedrally coordinated to the sulfur ions, and vice versa.<ref>Template:Cite book</ref> Minerals similar to sphalerite include those in the sphalerite group, consisting of sphalerite, colaradoite, hawleyite, metacinnabar, stilleite and tiemannite.<ref name="Cook-2003">Template:Cite journal</ref> The structure is closely related to the structure of diamond.<ref name="Klein-2017a" /> The hexagonal polymorph of sphalerite is wurtzite, and the trigonal polymorph is matraite.<ref name="Cook-2003" /> Wurtzite is the higher temperature polymorph, stable at temperatures above Template:Convert.<ref name="Deer-2013">Template:Cite book</ref> The lattice constant for zinc sulfide in the zinc blende crystal structure is 0.541 nm.<ref name="ICDD">International Centre for Diffraction Data reference 04-004-3804, ICCD reference 04-004-3804.</ref> Sphalerite has been found as a pseudomorph, taking the crystal structure of galena, tetrahedrite, barite and calcite.<ref name="Deer-2013" /><ref>Template:Cite book</ref> Sphalerite can have Spinel Law twins, where the twin axis is [111].
The chemical formula of sphalerite is Template:Chem2; the iron content generally increases with increasing formation temperature and can reach up to 40%.<ref name="Nesse-2013"/> The material can be considered a ternary compound between the binary endpoints ZnS and FeS with composition ZnxFe(1-x)S, where x can range from 1 (pure ZnS) to 0.6.Template:Cn
All natural sphalerite contains concentrations of various impurities, which generally substitute for zinc in the cation position in the lattice; the most common cation impurities are cadmium, mercury and manganese, but gallium, germanium and indium may also be present in relatively high concentrations (hundreds to thousands of ppm).<ref name="Cook-2009">Template:Cite journal</ref><ref name="Frenzel-2016">Template:Cite journal</ref> Cadmium can replace up to 1% of zinc and manganese is generally found in sphalerite with high iron abundances.<ref name="Cook-2003" /> Sulfur in the anion position can be substituted for by selenium and tellurium.<ref name="Cook-2003" /> The abundances of these impurities are controlled by the conditions under which the sphalerite formed; formation temperature, pressure, element availability and fluid composition are important controls.<ref name="Frenzel-2016" />
PropertiesEdit
Physical propertiesEdit
Sphalerite possesses perfect dodecahedral cleavage, having six cleavage planes.<ref name="Klein-2017a" /><ref name="Klein-2017b">Template:Cite book</ref> In pure form, it is a semiconductor, but transitions to a conductor as the iron content increases.<ref>Template:Cite journal</ref> It has a hardness of 3.5 to 4 on the Mohs scale of mineral hardness.<ref name=King/>
It can be distinguished from similar minerals by its perfect cleavage, its distinctive resinous luster, and the reddish-brown streak of the darker varieties.Template:Sfn
Optical propertiesEdit
Pure zinc sulfide is a wide-bandgap semiconductor, with bandgap of about 3.54 electron volts, which makes the pure material transparent in the visible spectrum. Increasing iron content will make the material opaque, while various impurities can give the crystal a variety of colors.<ref name=King>Hobart M. King, Sphalerite, geology.com. Retrieved 22 Feb. 2022.</ref> In thin section, sphalerite exhibits very high positive relief and appears colorless to pale yellow or brown, with no pleochroism.<ref name="Nesse-2013"/>
The refractive index of sphalerite (as measured via sodium light, average wavelength 589.3 nm) ranges from 2.37 when it is pure ZnS to 2.50 when there is 40% iron content.<ref name="Nesse-2013"/> Sphalerite is isotropic under cross-polarized light, however sphalerite can experience birefringence if intergrown with its polymorph wurtzite; the birefringence can increase from 0 (0% wurtzite) up to 0.022 (100% wurtzite).<ref name="Nesse-2013"/><ref name="Deer-2013" />
Depending on the impurities, sphalerite will fluoresce under ultraviolet light. Sphalerite can be triboluminescent.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Sphalerite has a characteristic triboluminescence of yellow-orange. Typically, specimens cut into end-slabs are ideal for displaying this property.Template:Cn
VarietiesEdit
Gemmy, colorless to pale green sphalerite from Franklin, New Jersey (see Franklin Furnace), are highly fluorescent orange and/or blue under longwave ultraviolet light and are known as cleiophane, an almost pure ZnS variety.<ref name="Manutchehr-Danai-2009">Template:Cite book</ref> Cleiophane contains less than 0.1% of iron in the sphalerite crystal structure.<ref name="Cook-2003" /> Marmatite or christophite is an opaque black variety of sphalerite and its coloring is due to high quantities of iron, which can reach up to 25%; marmatite is named after Marmato mining district in Colombia and christophite is named for the St. Christoph mine in Breitenbrunn, Saxony.<ref name="Manutchehr-Danai-2009" /> Both marmatite and cleiophane are not recognized by the International Mineralogical Association (IMA).<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> Red, orange or brownish-red sphalerite is termed ruby blende or ruby zinc, whereas dark colored sphalerite is termed black-jack.<ref name="Manutchehr-Danai-2009" />
Deposit typesEdit
Sphalerite is amongst the most common sulfide minerals, and it is found worldwide and in a variety of deposit types.<ref name="Rennie-Law-2016"/> The reason for the wide distribution of sphalerite is that it appears in many types of deposits; it is found in skarns,<ref>Template:Cite journal</ref> hydrothermal deposits,<ref>Template:Cite journal</ref> sedimentary beds,<ref>Template:Cite journal</ref> volcanogenic massive sulfide deposits (VMS),<ref>Template:Cite journal</ref> Mississippi-valley type deposits (MVT),<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref> granite<ref name="Cook-2003" /> and coal.<ref>Template:Cite journal</ref>
Sedimentary exhalitiveEdit
Approximately 50% of zinc (from sphalerite) and lead comes from Sedimentary exhalative (SEDEX) deposits, which are stratiform Pb-Zn sulfides that form at seafloor vents.<ref name="Kropschot-2011">Template:Cite journal</ref> The metals precipitate from hydrothermal fluids and are hosted by shales, carbonates and organic-rich siltstones in back-arc basins and failed continental rifts.<ref name="Arndt-2015">Template:Cite book</ref> The main ore minerals in SEDEX deposits are sphalerite, galena, pyrite, pyrrhotite and marcasite, with minor sulfosalts such as tetrahedrite-freibergite and boulangerite; the zinc + lead grade typically ranges between 10 and 20%.<ref name="Arndt-2015"/> Important SEDEX mines are Red Dog in Alaska, Sullivan Mine in British Columbia, Mount Isa and Broken Hill in Australia and Mehdiabad in Iran.<ref>Template:Cite journal</ref>
Mississippi-Valley typeEdit
Similar to SEDEX, Mississippi-Valley type (MVT) deposits are also a Pb-Zn deposit which contains sphalerite.<ref>Template:Citation</ref> However, they only account for 15–20% of zinc and lead, are 25% smaller in tonnage than SEDEX deposits and have lower grades of 5–10% Pb + Zn.<ref name="Arndt-2015"/> MVT deposits form from the replacement of carbonate host rocks such as dolostone and limestone by ore minerals; they are located in platforms and foreland thrust belts.<ref name="Arndt-2015"/> Furthermore, they are stratabound, typically Phanerozoic in age and epigenetic (form after the lithification of the carbonate host rocks).<ref name="Haldar-2020">Template:Citation</ref> The ore minerals are the same as SEDEX deposits: sphalerite, galena, pyrite, pyrrhotite and marcasite, with minor sulfosalts.<ref name="Haldar-2020" /> Mines that contain MVT deposits include Polaris in the Canadian arctic, Mississippi River in the United States, Pine Point in Northwest Territories, and Admiral Bay in Australia.<ref>Template:Cite journal</ref>
Volcanogenic massive sulfideEdit
Volcanogenic massive sulfide (VMS) deposits can be Cu-Zn- or Zn-Pb-Cu-rich, and accounts for 25% of Zn in reserves.<ref name="Arndt-2015"/> There are various types of VMS deposits with a range of regional contexts and host rock compositions; a common characteristic is that they are all hosted by submarine volcanic rocks.<ref name="Kropschot-2011"/> They form from metals such as copper and zinc being transferred by hydrothermal fluids (modified seawater) which leach them from volcanic rocks in the oceanic crust; the metal-saturated fluid rises through fractures and faults to the surface, where it cools and deposits the metals as a VMS deposit.<ref>Template:Cite book</ref> The most abundant ore minerals are pyrite, chalcopyrite, sphalerite and pyrrhotite.<ref name="Arndt-2015" /> Mines that contain VMS deposits include Kidd Creek in Ontario, Urals in Russia, Troodos in Cyprus, and Besshi in Japan.<ref>Template:Cite journal</ref>
LocalitiesEdit
The top producers of sphalerite include the United States, Russia, Mexico, Germany, Australia, Canada, China, Ireland, Peru, Kazakhstan and England.<ref>Template:Cite journal</ref><ref name="Routledge-2003">Template:Cite book</ref>
Sources of high quality crystals include:
| Place | Country |
|---|---|
| Freiberg, Saxony, Neudorf, Harz Mountains |
Germany |
| Lengenbach Quarry, Binntal, Valais | Switzerland |
| Horní Slavkov and Příbram | Czech Republic |
| Rodna | Romania |
| Madan, Smolyan Province, Rhodope Mountains | Bulgaria |
| Aliva mine, Picos de Europa Mountains, Cantabria [Santander] Province | Spain |
| Alston Moor, Cumbria | England |
| Dalnegorsk, Primorskiy Kray | Russia |
| Watson Lake, Yukon Territory | Canada |
| Flin Flon, Manitoba | Canada |
| Tri-State district including deposits near Baxter Springs, Cherokee County, Kansas; Joplin, Jasper County, Missouri and Picher, Ottawa County, Oklahoma |
US |
| Elmwood mine, near Carthage, Smith County, Tennessee | US |
| Eagle mine, Gilman district, Eagle County, Colorado | US |
| Santa Eulalia, Chihuahua | Mexico |
| Naica, Chihuahua | Mexico |
| Cananea, Sonora | Mexico |
| Huaron | Peru |
| Casapalca | Peru |
| Huancavelica | Peru |
| Zinkgruvan | Sweden |
UsesEdit
Metal oreEdit
Sphalerite is an important ore of zinc; around 95% of all primary zinc is extracted from sphalerite ore.<ref name=USGS>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> However, due to its variable trace element content, sphalerite is also an important source of several other metals such as cadmium,<ref>Template:Cite book</ref> gallium,<ref>Template:Cite journal</ref> germanium,<ref>Template:Cite journal</ref> and indium<ref>Template:Cite journal</ref> which replace zinc. The ore was originally called blende by miners (from German blind or deceiving) because it resembles galena but yields no lead.Template:Sfn
Brass and bronzeEdit
The zinc in sphalerite is used to produce brass, an alloy of copper with 3–45% zinc.<ref name="Klein-2017b"/> Major element alloy compositions of brass objects provide evidence that sphalerite was being used to produce brass by the Islamic as far back as the medieval ages between the 7th and 16th century CE.<ref>Template:Cite book</ref> Sphalerite may have also been used during the cementation process of brass in Northern China during the 12th–13th century CE (Jin Dynasty).<ref>Template:Cite journal</ref> Besides brass, the zinc in sphalerite can also be used to produce certain types of bronze; bronze is dominantly copper which is alloyed with other metals such as tin, zinc, lead, nickel, iron and arsenic.<ref>Template:Cite book</ref>
OtherEdit
- Yule Marble – sphalerite is found as inclusions in yule marble, which is used as a building material for the Lincoln Memorial and Tomb of the Unknown.<ref>Template:Cite book</ref>
- Galvanized iron – zinc from sphalerite is used as a protective coating to prevent corrosion and rusting; it is used on power transmission towers, nails and automobiles.<ref name="Routledge-2003"/>
- Batteries.<ref>Template:Cite journal</ref>
- Gemstone.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref>
GalleryEdit
- Sphalerite-barite (Cumberland Mine, Smith County, Tennessee, USA).jpg
Sphalerite and barite from Cumberland Mine, Tennessee, US
- Sphalerite on dolostone (Millersville Quarry, Sandusky County, Ohio, USA).jpg
Sphalerite on dolostone, from Millersville Quarry, Ohio, US
- Calcite-Sphalerite-elm05b.jpg
Tan crystal of calcite attached to a cluster of black sphalerite crystals
- Sphalerite-221270.jpg
Sharp, tetrahedral sphalerite crystals with minor associated chalcopyrite from the Idarado Mine, Telluride, Ouray District, Colorado, US
- Sphalerite-Quartz-261762.jpg
Gem quality twinned cherry-red sphalerite crystal (1.8 cm) from Hunan Province, China
- Esfalerita (Blenda acaramelada) Áliva, Cantabria.jpg
Sphalerite crystals from Áliva, Camaleño, Cantabria (Spain)
- Fluorite and sphalerite J1.jpg
Purple fluorite and sphalerite, from the Elmwood mine, Smith county, Tennessee, US
- Geodized brachiopod.jpg
Sphalerite crystal in geodized brachiopod
See alsoEdit
ReferencesEdit
Further readingEdit
- Dana's Manual of Mineralogy Template:ISBN
- Webster, R., Read, P. G. (Ed.) (2000). Gems: Their sources, descriptions and identification (5th ed.), p. 386. Butterworth-Heinemann, Great Britain. Template:ISBN