Sphalerite mineral is in group of Sulfide mineral that is formula ((Zn, Fe)S).It is the principal ore of zinc. Pure sphalerite is colorless and rare. Normally, iron is present, causing the color to vary from pale greenish yellow to brown and black with increasing iron content. When iron content is high it is an opaque black variety, marmatite. It is usually found in association with galena, pyrite, and other sulfides along with calcite, dolomite, and fluorite. Miners have also been known to refer to sphalerite as zinc blende, black-jack and ruby jack. Its complex crystals combine tetrahedral or dodecahedral forms with other faces. Sphalerite gets its name from the Greek sphaleros, meaning “deceitful,” because its lustrous dark crystals can be mistaken for other minerals. It is often coarsely crystalline or massive, or forms banded, botryoidal, or stalactitic aggregates. Sphalerite is found associated with galena in lead-zinc deposits. It occurs in hydrothermal vein deposits, contact metamorphic zones, and replacement deposits formed at high temperature (1,065°F/575°C or above). It is also found in meteorites and lunar rocks.
Name: From theGreek for treacherous, the mineral sometimes being mistaken for galena, butyielding no lead.
Association: Galena, chalcopyrite, marcasite, pyrite, fluorite, barite, quartz, many other hydrothermal minerals.
Polymorphism &Series: Trimorphous with matraite and wurtzite
Mineral Group: Sphaleritegroup.
Cell Data: SpaceGroup: F43m. a = 5.4060 Z = 4
X-ray Powder Pattern:Synthetic ZnS. 3.123 (100), 1.912 (51), 1.561 (30), 2.705 (10), 1.240 (9),1.1034 (9), 1.351 (6)
Economic importance:Sphalerite is the most important zinc ore. Approximately 95% of all primaryzinc is extracted from sphalerite ores. However, due to the variable traceelement content, sphalerite is an important source of many other elements suchas cadmium, gallium, germanium and indium.
Contents
- Varieties
- Composition
- Chemical Properties
- Sphalerite Physical Properties
- Sphalerite Optical Properties
- Sphalerite Occurrence
- Uses Area
- Sphalerite Distribution
- References
Varieties
In some examples the gray-black crystals have rediridescence; These are called “ruby sphalerites.” The pale yellow andred varieties have very little iron and are translucent. Darker, more opaquevarieties contain more iron. Some samples are also fluorescent in ultravioletlight.
Pale samples from Gemmy, Franklin, New Jersey (see FranklinQuarry) are highly fluorescent orange and / or blue in long wave ultravioletlight and are known as cleiophane, an almost pure ZnS variety.
Composition
The chemical formula (Zn, Fe) of sphalerite is S. It is azinc sulphide containing a variable amount of iron instead of zinc in themineral lattice. The iron content is normally less than 25% by weight. Theamount of iron substitution formed depends on the availability and temperatureof the iron, with higher temperatures preferring a higher iron content.
Sphalerite generally contains small amounts of cadmium,indium, germanium or gallium trace. These rare elements are valuable and can berecovered as profitable by-products when they are abundant enough. Smallamounts of manganese and arsenic may also be present in the sphalerite.
Chemical Properties
| Chemical Classification | Sulfide mineral |
| Formula | (Zn,Fe)S |
| Common Impurities | Mn,Cd,Hg,In,Tl,Ga,Ge,Sb,Sn,Pb,Ag |
Sphalerite Physical Properties
| Color | Yellow,light to dark brown, black, red-brown, colourless, light blue. green |
| Streak | Paleyellow to brown. |
| Luster | Adamantine,Resinous |
| Cleavage | PerfectPerfect {011} |
| Diaphaneity | Transparent, Translucent |
| Mohs Hardness | 3,5 – 4 |
| Crystal System | Isometric |
| Tenacity | Brittle |
| Density | 3.9 – 4.1 g/cm3 (Measured) 4.096 g/cm3 (Calculated) |
| Fracture | Conchoidal |
| Crystal habit | Euhedral crystals – occurs as well-formed crystalsshowing good external form. Granular – generally occurs as anhedral tosubhedral crystals in matrix. |
| Other characteristics | non-radioactive, non-magnetic, fluorescent andtriboluminescent. |
Sphalerite Optical Properties
| Type | Isotropic |
| RIvalues: | nα = 2.369 |
| Twinning | Simple contact twins or complex lamellar forms, twinaxis [111] |
| Birefringence | Isotropic minerals have no birefringence |
| Relief | Moderate |
Sphalerite Occurrence
Formed under a wide range of low- to high-temperaturehydrothermal conditions; in coal, limestone, and other sedimentary deposits.
Sphalerite, the most important ore of the zinc ore, is avery common mineral and is associated with galena, pyrite, marcasite,chalcopyrite, smithsonite, calcite and dolomite. In its formation and originmode, it is closely related to the most common galena. It is widelydistributed, but is mainly found in veins and irregular displacement beds inlimestone. Sphalerite is also found in veins and contact metamorphic depositsin igneous rocks.
Uses Area
It is used as gemstone. Crystals of suitable size andtransparency have been fashioned into gemstones, usually featuring thebrilliant cut to best display sphalerite’s high dispersion of 0.156 (B-Ginterval), over three times that of diamond. Freshly cut gems have anadamantine luster. Owing to their softness and fragility the gems are oftenleft unset as collectors or museum pieces (although some have been set intopendants).
The most important ore of zinc. The chief uses for metalliczinc, or spelter, are in galvanizing iron; making brass, an alloy of copper andzinc; in electric batteries; and as sheet zinc. Zinc oxide, or zinc white, isused extensively for making paint. Zinc chloride is used as a preservative forwood. Zinc sulfate is used in dyeing and in medicine. Sphalerite also serves asthe most important source of cadmium.
Sphalerite Distribution
The most important ore of zinc. Only a few localities forthe finest crystallized examples can be given.
- In Germany, from Freiberg, Saxony, and Neudorf,Harz Mountains.
- Colorless crystals in the Lengenbach quarry,Binntal, Valais, Switzerland.
- At Hornı Slavkov (Schlaggenwald) and Prıbram,Czech Republic.
- From Rodna, Romania. Transparent crystals in theAliva mine, Picos de Europa Mountains, Cantabria [Santander] Province, Spain.
- In England, from Alston Moor, Cumbria. AtDal’negorsk, Primorskiy Kray, Russia.
- From Watson Lake, Yukon Territory, Canada.
- In the USA, in the Tri-State district of theMississippi Valley; near Baxter Springs, Cherokee Co., Kansas; Joplin, JasperCo., Missouri and Picher, Ottawa Co., Oklahoma.
- From the Elmwood mine, near Carthage, Smith Co.,Tennessee; in the Eagle mine, Gilman district, Eagle Co., Colorado.
- In Mexico, from Santa Eulalia and Naica,Chihuahua, and Cananea, Sonora.
- At Huaron, Casapalca, and Huancavelica, Peru
References
- Bonewitz, R. (2012). Rocks and minerals. 2nd ed. London: DK Publishing.
- Dana, J. D. (1864). Manual of Mineralogy… Wiley.
- Handbookofmineralogy.org. (2019). Handbook of Mineralogy. [online] Available at: http://www.handbookofmineralogy.org [Accessed 4 Mar. 2019].
- Mindat.org. (2019): Mineral information, data and localities.. [online] Available at: https://www.mindat.org/ [Accessed. 2019].
- Wikipedia contributors. (2019, April 26). Sphalerite. InWikipedia, The Free Encyclopedia. Retrieved 02:50, June 24, 2019, fromhttps://en.wikipedia.org/w/index.php?title=Sphalerite&oldid=894261404
