Smithsonite, also known as zinc spar, is the mineral form of

zinc carbonate Zinc carbonate is the inorganic compound with the formula ZnCO3. It is a white solid that is insoluble in water. It exists in nature as the mineral smithsonite. It is prepared by treating cold solutions of zinc sulfate with potassium bicarbonat ...

( Zn CO₃). Historically, smithsonite was identified with

hemimorphite Hemimorphite is the chemical compound Zn4( Si2O7)( OH)2 ·H2O, a component of mineral calamine. It is a silicate mineral which, together with smithsonite (ZnCO3), has been historically mined from the upper parts of zinc and lead ores. Both ...

before it was realized that they were two different minerals. The two minerals are very similar in appearance and the term

calamine Calamine, also known as calamine lotion, is a medication used to treat mild itchiness. This includes from sunburn, insect bites, poison ivy, poison oak, and other mild skin conditions. It may also help dry out skin irritation. It is applied ...

has been used for both, leading to some confusion. The distinct mineral smithsonite was named in 1832 by

François Sulpice Beudant François Sulpice Beudant (5 September 1787 – 10 December 1850), was a French mineralogist and geologist. The mineral beudantite was named after him. Life He was born in Paris. He was educated at the Ecole Polytechnique and Ecole Normale, an ...

in honor of

English English usually refers to: * English language * English people English may also refer to: Peoples, culture, and language * ''English'', an adjective for something of, from, or related to England ** English national ide ...

chemist A chemist (from Greek ''chēm(ía)'' alchemy; replacing ''chymist'' from Medieval Latin ''alchemist'') is a scientist trained in the study of chemistry. Chemists study the composition of matter and its properties. Chemists carefully describe th ...

and

mineralogist Mineralogy is a subject of geology specializing in the scientific study of the chemistry, crystal structure, and physical (including optical) properties of minerals and mineralized artifacts. Specific studies within mineralogy include the proce ...

James Smithson James Smithson (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 ...

(c.1765–1829), who first identified the mineral in 1802. Smithsonite is a variably colored

trigonal In crystallography, the hexagonal crystal family is one of the six crystal families, which includes two crystal systems (hexagonal and trigonal) and two lattice systems (hexagonal and rhombohedral). While commonly confused, the trigonal crysta ...

mineral which only rarely is found in well formed crystals. The typical habit is as earthy

botryoidal A botryoidal ( ) texture or mineral habit, is one in which the mineral has an external form composed of many rounded segments, named for the Ancient Greek (), meaning "a bunch of grapes".Adjective form: ''botruoeidēs'' This is a common form f ...

masses. It has a

Mohs hardness The Mohs scale of mineral hardness () is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material. The scale was introduced in 1812 by th ...

of 4.5 and a

specific gravity Relative density, or specific gravity, is the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for liquids is nearly always measured with respect to water (molecule), wa ...

of 4.4 to 4.5. Smithsonite occurs as a secondary mineral in the

weathering Weathering is the deterioration of rocks, soils and minerals as well as wood and artificial materials through contact with water, atmospheric gases, and biological organisms. Weathering occurs ''in situ'' (on site, with little or no movement), ...

oxidation Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a d ...

zone of zinc-bearing

ore Ore is natural rock or sediment that contains one or more valuable minerals, typically containing metals, that can be mined, treated and sold at a profit.Encyclopædia Britannica. "Ore". Encyclopædia Britannica Online. Retrieved 7 Apr ...

deposits. It sometimes occurs as replacement bodies in

carbonate rock Carbonate rocks are a class of sedimentary rocks composed primarily of carbonate minerals. The two major types are limestone, which is composed of calcite or aragonite (different crystal forms of CaCO3), and dolomite rock (also known as dolosto ...

s and as such may constitute zinc ore. It commonly occurs in association with hemimorphite,

willemite Willemite is a zinc silicate mineral () and a minor ore of zinc. It is highly fluorescent (green) under shortwave ultraviolet light. It occurs in a variety of colors in daylight, in fibrous masses and apple-green gemmy masses. Troostite is a vari ...

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 incru ...

cerussite Cerussite (also known as lead carbonate or white lead ore) is a mineral consisting of lead carbonate (PbCO3), and is an important ore of lead. The name is from the Latin ''cerussa'', white lead. ''Cerussa nativa'' was mentioned by Conrad Gessner ...

malachite Malachite is a copper carbonate hydroxide mineral, with the formula Cu2CO3(OH)2. This opaque, green-banded mineral crystallizes in the monoclinic crystal system, and most often forms botryoidal, fibrous, or stalagmitic masses, in fractures ...

azurite Azurite is a soft, deep-blue copper mineral produced by weathering of copper ore deposits. During the early 19th century, it was also known as chessylite, after the Type locality (geology), type locality at Chessy, Rhône, Chessy-les-Mines near ...

aurichalcite Aurichalcite is a carbonate mineral, usually found as a secondary mineral in copper and zinc deposits. Its chemical formula is . The zinc to copper ratio is about 5:4. Occurrence Aurichalcite typically occurs in the oxidized zone of copper and z ...

and

anglesite Anglesite is a lead sulfate mineral with the chemical formula PbSO4. It occurs as an oxidation product of primary lead sulfide ore, galena. Anglesite occurs as prismatic orthorhombic crystals and earthy masses, and is isomorphous with barite and ...

. It forms two limited

solid solution A solid solution, a term popularly used for metals, is a homogenous mixture of two different kinds of atoms in solid state and have a single crystal structure. Many examples can be found in metallurgy, geology, and solid-state chemistry. The word ...

series, with substitution of

manganese Manganese is a chemical element with the symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese is a transition metal with a multifaceted array of industrial alloy use ...

leading to

rhodochrosite Rhodochrosite is a manganese carbonate mineral with chemical composition MnCO3. In its (rare) pure form, it is typically a rose-red color, but impure specimens can be shades of pink to pale brown. It streaks white, and its Mohs hardness varies bet ...

, and with

iron Iron () is a chemical element with symbol Fe (from la, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, right in f ...

, leading to

siderite 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 ...

. A variety rich in

cadmium Cadmium is a chemical element with the symbol Cd and atomic number 48. This soft, silvery-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Like zinc, it demonstrates oxidation state +2 in most of ...

, which gives it a bright yellow color, is sometimes called ''turkey fat ore''.

Gallery

File:Smithsonite 4.JPG, Crystals of smithsonite: Ojuela Mine, Mapimi, Mun. de Mapimi, Durango, Mexico File:Smithsonite-52236.jpg, Crystals of pink Cobaltoan smithsonite on matrix File:Smithsonite-279094.jpg, Apple-green Cuprian smithsonite crystals. A second generation of

drusy In geology, druse refers to a coating of fine crystals on a rock fracture surface or vein or within a vug or geode. See also * Crystal habit In mineralogy, crystal habit is the characteristic external shape of an individual crystal or crys ...

smithsonite was deposited in the crevasses between the larger growth File:Smithsonite-139792.jpg, Crystals of slightly pink cobaltoan smithsonite, Tsumeb, 6.8 x 4.6 x 3.7 cm File:Smithsonite Kelly Mine.jpg, Blue smithsonite from the Kelly Mine in New Mexico

References

Bibliography

* Tom Hughes, Suzanne Liebetrau, and Gloria Staebler, eds. (2010). ''Smithsonite: Think Zinc!'' Denver, CO: Lithographie . * Ewing, Heather (2007). ''The Lost World of James Smithson: Science, Revolution, and the Birth of the Smithsonian.'' London and New York: Bloomsbury

External links

James Smithson's 1802 Calamine Paper
{{Authority control Carbonate minerals Zinc minerals Calcite group Trigonal minerals Minerals in space group 167 Minerals described in 1802