a = 7.6222(5) Å, b = 9.0448(7) Å, c = 4.5348(4) Å; Z = 4
Identification
Color
Colorless to white, pale green, pale yellow
Crystal habit
As elongated, flattened prismatic crystals; in aggregates of radiating sprays; granular, crustiform or pseudomorphs
Cleavage
Perfect on {010}
Fracture
Subconchoidal
Tenacity
Slightly sectile
Mohs scale hardness
2.5
Luster
Adamantine, silky to pearly
Diaphaneity
Transparent to opaque
Specific gravity
5.80
Optical properties
Biaxial (+)
Refractive index
nα = 2.199 nβ = 2.217 nγ = 2.260
Birefringence
δ = 0.061
2V angle
Measured: 67°
Solubility
Slight in water
References
[2][3][4]
Cotunnite is the natural mineral form of lead(II) chloride (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 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, Italy; Tarapacá, Chile; and Tolbachik, Russia.[5]
It was first described in 1825 from an occurrence on Mount Vesuvius, Naples Province, Campania, Italy.[3] It was named for Domenico Cotugno (Cotunnius) (1736–1822), Italian physician and Professor of Anatomy.[2]
It was first recognized in volcanic 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.[2][6]
It occurs in association with galena, cerussite, anglesite and matlockite in the Caracoles, Chile. At the Tolbachik volcano on the Kamchatka Peninsula, Russia it occurs with the rare to uncommon minerals tenorite, ponomarevite, sofiite, burnsite, ilinskite, georgbokite, chloromenite, halite, sylvite and native gold.[2]
Cotunnite is the natural mineral form of lead(II) chloride (PbCl2). Unlike the pure compound, which is white, cotunnite can be white, yellow, or green...
coordination of Ba2+ is 8 in the fluorite structure and 9 in the cotunnite structure. When cotunnite-structure BaCl2 is subjected to pressures of 7–10 GPa, it...
four high-pressure forms (α-PbO2-like, cotunnite-like, orthorhombic OI, and cubic phases) also exist: The cotunnite-type phase was claimed to be the hardest...
Haines, J.; Atouf, A. (1996). "The high pressure behaviour of the cotunnite and post-cotunnite phases of PbCl2 and SnCl 2". J. Phys. Chem. Solids. 57 (1): 7–16...
As a sublimate it occurs with copper chlorides, alkali chlorides and cotunnite. The Vesuvian sublimate occurrence was originally named melaconise or...
chloride may refer to: Lead(II) chloride (plumbous chloride), mineral name: cotunnite. Lead(IV) chloride (plumbic chloride) This set index article lists chemical...
solvents with which they do not react. CaH2 crystallizes in the PbCl2 (cotunnite) structure. Calcium hydride is prepared from its elements by direct combination...
ionic and hygroscopic in nature. BaBr2 crystallizes in the lead chloride (cotunnite) motif, giving white orthorhombic crystals that are deliquescent. In aqueous...
white fumarolic encrustations on lava. It occurs as intergrowths with cotunnite. It was first described from a finding at the Challacollo Mine, Iquique...
Houtermans on age determinations of Congolese minerals and radioactive bleach (Cotunnites) from Mount Vesuvius. He refused a call to the Johannes Gutenberg University...
paralaurionite, while the Italian specimens were found in association with cotunnite and fiedlerite. S., Merlino; M., Pasero; N., Perchiazzi; M., Gianfagna...
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