Cerussite (also known as lead carbonate or white lead ore) is a

mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid substance with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2011): Mi ...

consisting of lead carbonate with the chemical formula PbCO₃, and is an important ore of lead. The name is from the

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''cerussa'', white lead. ''Cerussa nativa'' was mentioned by Conrad Gessner in 1565, and in 1832 F. S. Beudant applied the name ''céruse'' to the mineral, whilst the present form, cerussite, is due to W. Haidinger (1845). Miners' names in early use were lead-spar and white-lead-ore. Cerussite

crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macros ...

lizes in the

orthorhombic crystal system In crystallography, the orthorhombic crystal system is one of the 7 crystal systems. Orthorhombic lattices result from stretching a cubic lattice along two of its orthogonal pairs by two different factors, resulting in a rectangular prism with ...

and is isomorphous with

aragonite Aragonite is a carbonate mineral and one of the three most common naturally occurring crystal forms of calcium carbonate (), the others being calcite and vaterite. It is formed by biological and physical processes, including precipitation fr ...

. Like aragonite it is very frequently twinned, the compound crystals being pseudo-hexagonal in form. Three crystals are usually twinned together on two faces of the prism, producing six-rayed stellate groups with the individual crystals intercrossing at angles of nearly 60°. Crystals are of frequent occurrence and they usually have very bright and smooth faces. The mineral also occurs in compact granular masses, and sometimes in fibrous forms. The mineral is usually colorless or white, sometimes grey or greenish in tint and varies from transparent to translucent with an adamantine lustre. It is very brittle, and has a

conchoidal fracture A conchoidal fracture is a break or fracture of a brittle material that does not follow any natural planes of separation. Mindat.org defines ''conchoidal fracture'' as follows: "a fracture with smooth, curved surfaces, typically slightly concave ...

. 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 3 to 3.75 and a specific gravity of 6.5. A variety containing 7% of zinc carbonate, replacing lead carbonate, is known as iglesiasite, from Iglesias in

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, where it is found. The mineral may be readily recognized by its characteristic twinning, in conjunction with the adamantine lustre and high specific gravity. It dissolves with effervescence in dilute

nitric acid Nitric acid is an inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but samples tend to acquire a yellow cast over time due to decomposition into nitrogen oxide, oxides of nitrogen. Most com ...

. A blowpipe test will cause it to fuse very readily, and gives indications for lead. Finely crystallized specimens have been obtained from the Friedrichssegen mine in Lahnstein in

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, Johanngeorgenstadt in

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in the

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, Phoenixville in

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, Broken Hill in New South Wales, and several other localities. Delicate acicular crystals of considerable length were found long ago in the Pentire Glaze mine near St Minver in

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. Cerussite is often found in considerable quantities, and has a lead content of up to 77.5%. Lead(II) carbonate is practically insoluble in neutral water (solubility product b²⁺CO₃²⁻] ≈ 1.5×10⁻¹³ at 25 °C), but will dissolve in dilute acids.

Commercial uses

" White lead" is the key ingredient in (now discontinued) lead paints. Ingestion of lead-based paint chips is the most common cause of

lead poisoning Lead poisoning, also known as plumbism and saturnism, is a type of metal poisoning caused by lead in the body. Symptoms may include abdominal pain, constipation, headaches, irritability, memory problems, infertility, numbness and paresthesia, t ...

in children. Both "white lead" and lead acetate have been used in cosmetics throughout history, though this practice has ceased in Western countries.

Gallery

File:cerussite09.jpg,

Crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macros ...

s of cerussite, a secondary lead ore File:Light of the Desert.jpg, At 890 carats, the Light of the Desert (located at

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) is the world's largest faceted cerussite. File:Cerussite-Malachite-Mimetite-158529.jpg, Colorless cerussite crystal that has been included by wisps of light green malachite File:Cerussite-18566.jpg, Fine example of reticulated growth

References

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External links

Mineral galleries
Carbonate minerals Gemstones Lead minerals Luminescent minerals Minerals in space group 62 Orthorhombic minerals Aragonite group Minerals described in 1845

Commercial uses

Gallery

See also

References

External links