Smithsonite, also known as zinc spar, is the mineral form of
zinc carbonate (
Zn CO3). Historically, smithsonite was identified with
hemimorphite 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 made from powdered calamine (mineral), calamine mineral that is used to treat mild itchiness. Conditions treated include sunburn, insect bites, Toxicodendron radicans, poison ivy, poiso ...
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 scientist
James Smithson (c. 1765–1829), who first identified the mineral in 1802.
trigonal
In crystallography, the hexagonal crystal family is one of the six crystal family, crystal families, which includes two crystal systems (hexagonal and trigonal) and two lattice systems (hexagonal and rhombohedral). While commonly confused, the tr ...
mineral which only rarely is found in well formed crystals. The typical habit is as earthy botryoidal 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 mineral
In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fair ...
of 4.5 and a specific gravity
Relative density, also called specific gravity, is a dimensionless quantity defined as the ratio of the density (mass of a unit volume) of a substance to the density of a given reference material. Specific gravity for solids and liquids is nea ...
of 4.4 to 4.5.
Smithsonite occurs as a secondary mineral in the weathering or oxidation
Redox ( , , reduction–oxidation or oxidation–reduction) is a type of chemical reaction in which the oxidation states of the reactants change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is ...
zone of zinc-bearing ore 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), dolomite rock (also kn ...
s 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
A solid solution, a term popularly used for metals, is a homogeneous mixture of two compounds in solid state and having a single crystal structure. Many examples can be found in metallurgy, geology, and solid-state chemistry. The word "solutio ...
series, with substitution of manganese
Manganese is a chemical element; it has Symbol (chemistry), symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese was first isolated in the 1770s. It is a transition m ...
leading to rhodochrosite
Rhodochrosite is a manganese carbonate mineral with chemical composition Manganese(II) carbonate, MnCO3. In its pure form (rare), it is typically a rose-red colour, but it can also be shades of pink to pale brown. It Streak (mineralogy), streak ...
, and with iron
Iron is a chemical element; it has symbol Fe () 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, forming much of Earth's o ...
, leading to siderite.[ A bright yellow variety is sometimes called "turkey fat ore". The cause of the yellow colour is due to the presence of greenockite inclusions within the smithsonite crystals.][
]
Gallery
File:Smithsonite 4.JPG, Botryoidal smithsonite: Ojuela Mine, Mapimi, Mun. de Mapimi, Durango, Mexico
File:SmithsoniteGrece.jpg, Botryoidal smithsonite mass from the Lavrion District Mines, Greece
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 smithsonite was deposited in the crevasses between the larger growth.
File:Smithsonite-139792.jpg, Crystals of slightly pink cobaltoan smithsonite, Tsumeb, 6.8 × 4.6 × 3.7 cm
File:Smithsonite Kelly Mine.jpg, Blue smithsonite from the Kelly Mine in New Mexico
See also
* List of minerals
* List of minerals named after people
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