Cotunnite is the natural mineral form of

lead(II) chloride Lead(II) chloride (PbCl2) is an inorganic compound which is a white solid under ambient conditions. It is poorly soluble in water. Lead(II) chloride is one of the most important lead-based reagents. It also occurs naturally in the form of the min ...

(PbCl₂). Unlike the pure compound, which is white, cotunnite can be white, yellow, or green. The density of mineral samples spans range 5.3–5.8 g/cm³. The hardness on the

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

is 1.5–2. The crystal structure is orthorhombic dipyramidal and the point group is 2/m 2/m 2/m. Each Pb has a coordination number of 9. Cotunnite occurs near volcanoes:

Vesuvius Mount Vesuvius ( ) is a Somma volcano, somma–stratovolcano located on the Gulf of Naples in Campania, Italy, about east of Naples and a short distance from the shore. It is one of several volcanoes forming the Campanian volcanic arc. Vesuv ...

, Italy; Tarapacá, Chile; and

Tolbachik Tolbachik () is a complex volcano, volcanic complex on the Kamchatka Peninsula in the far east of Russia. It consists of two volcanoes, Plosky (''flat'') Tolbachik (3,085 m) and Ostry (''sharp'') Tolbachik (3,672 m), which as the names suggest a ...

, Russia. It was first described in 1825 from an occurrence on

Mount Vesuvius Mount Vesuvius ( ) is a Somma volcano, somma–stratovolcano located on the Gulf of Naples in Campania, Italy, about east of Naples and a short distance from the shore. It is one of several volcanoes forming the Campanian volcanic arc. Vesuv ...

, Naples Province,

Campania Campania is an administrative Regions of Italy, region of Italy located in Southern Italy; most of it is in the south-western portion of the Italian Peninsula (with the Tyrrhenian Sea to its west), but it also includes the small Phlegraean Islan ...

, Italy. It was named for

Domenico Cotugno Domenico Felice Antonio Cotugno (January 29, 1736 – October 6, 1822) was an Italian people, Italian physician. Biography Born at Ruvo di Puglia (Province of Bari, Apulia) into a family of humble means, Cotugno underwent physical and economic ...

(Cotunnius) (1736–1822), Italian physician and Professor of Anatomy. It was first recognized in

volcanic A volcano is commonly defined as a vent or fissure in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often fo ...

fumarole deposits. It occurs as a secondary alteration product in lead ore deposits. It has also been reported as an alteration of archaeological objects that contain lead.Late-Hellenistic shipwreck, Mahdia, Tunisia, (Mindat locality)
/ref> It occurs in association with

galena Galena, also called lead glance, is the natural mineral form of lead(II) sulfide (PbS). It is the most important ore of lead and an important source of silver. Galena is one of the most abundant and widely distributed sulfide minerals. It crysta ...

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

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 ...

and matlockite in the Caracoles,

Chile Chile, officially the Republic of Chile, is a country in western South America. It is the southernmost country in the world and the closest to Antarctica, stretching along a narrow strip of land between the Andes, Andes Mountains and the Paci ...

. At the

volcano on the

Kamchatka Peninsula The Kamchatka Peninsula (, ) is a peninsula in the Russian Far East, with an area of about . The Pacific Ocean and the Sea of Okhotsk make up the peninsula's eastern and western coastlines, respectively. Immediately offshore along the Pacific ...

, it occurs with the rare to uncommon minerals tenorite, ponomarevite, sofiite, burnsite, ilinskite, georgbokite, chloromenite,

halite Halite ( ), commonly known as rock salt, is a type of salt, the mineral (natural) form of sodium chloride ( Na Cl). Halite forms isometric crystals. The mineral is typically colorless or white, but may also be light blue, dark blue, purple, pi ...

sylvite Sylvite, or sylvine, is potassium chloride (KCl) in natural mineral form. It forms crystals in the isometric system very similar to normal rock salt, halite ( NaCl). The two are, in fact, isomorphous. Sylvite is colorless to white with shades ...

and native gold.

References

Halide minerals Lead minerals Orthorhombic minerals Minerals in space group 62 {{halide-mineral-stub