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Phosgenite

Rare mineral

Summary

Rare mineral

Field	Value
name	Phosgenite
boxbgcolor	#C4B353
image	Phosgenite-34631.jpg
caption	Crystal of phosgenite from the Monteponi Mine, Iglesias, Sardinia, Italy (size: 3.0 x 3.0 x 2.5 cm)
category	Carbonate minerals
formula	(PbCl)2CO3
IMAsymbol	Pho
strunz	5.BE.20
system	Tetragonal
class	Ditetragonal dipyramidal (4/mmm)
H-M symbol: (4/m 2/m 2/m)
symmetry	P4/mbm
unit cell	a = 8.16 Å, c = 8.883(6) Å; Z = 4
color	Pale yellow to yellowish brown, pale brown, smoky brown, smoky violet, colorless, pale rose, gray, yellowish gray, pale green
habit	Short prismatic crystals, granular, massive
cleavage	Distinct on {001} and {110}, indistinct on {100}
fracture	Conchoidal
tenacity	Sectile, flexible perpendicular to {001}
mohs	2–3
luster	Adamantine
streak	White
diaphaneity	Transparent to translucent
gravity	6.12 – 6.15
opticalprop	Uniaxial (+); anomalously biaxial if strained
refractive	nω = 2.118 nε = 2.145
birefringence	δ = 0.027
pleochroism	Weakly pleochroic with O – reddish and E – greenish in thick sections.
fluorescence	Fluoresces yellow under LW and SW UV
solubility	Soluble in dilute nitric acid with effervescence, decomposes slowly in cold water
references

H-M symbol: (4/m 2/m 2/m) | length fast/slow =

Phosgenite is a rare mineral consisting of lead carbonate chloride, (PbCl)2CO3. The tetragonal crystals are prismatic or tabular in habit: they are usually colorless and transparent, and have a brilliant adamantine lustre. Sometimes the crystals have a curious helical twist about the tetrad or principal axis. The hardness is 3 and the specific gravity 6.3. The mineral is rather sectile, and consequently was earlier known as corneous lead ().

Name and occurrence

An example of the mineral Phosgenite on display at the [[Royal Ontario Museum

The name phosgenite was given by August Breithaupt in 1820, after phosgene, carbon oxychloride, because the mineral contains the elements carbon, oxygen, and chlorine.

It was found associated with anglesite and matlockite in cavities within altered galena in a lead mine at Cromford, near Matlock: hence its common name cromfordite. Crystals are also found in galena at Monteponi near Iglesias in Sardinia, and near Dundas in Tasmania. It has also been reported from Laurium, Greece; Tarnowitz, Poland; the Altai district, Siberia; the Touissit mine, near Oujda, Morocco; Sidi Amor ben Salem, Tunisia; Tsumeb, Namibia; Broken Hill, New South Wales; and Boleo, near Santa Rosalía, Baja California Sur. In the US it has been reported from the Terrible mine, Custer County, Colorado; the Stevenson-Bennett mine, Organ Mountains, Doña Ana County, New Mexico; and the Mammoth mine, Tiger, Pinal County, Arizona.

Crystals of phosgenite, and also of the corresponding bromine compound (PbBr)2CO3, have been prepared artificially.

References

Warr, L.N.. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine.
[https://www.mineralienatlas.de/lexikon/index.php/MineralData?mineral=Phosgenite Mineralienatlas]
[http://rruff.geo.arizona.edu/doclib/hom/phosgenite.pdf Handbook of Mineralogy]
[http://www.mindat.org/min-3195.html Mindat.org]
[http://www.webmineral.com/data/Phosgenite.shtml Webmineral data]
{{EB1911. Leonard James. Spencer
[http://www.mindat.org/jrs/JRS%20Vol%2001-2.pdf "Phosgenite and Matlockite in Derbyshire (Part 1). T. Bridges, M. E. Smith.] Journal of the Russell Society Volume 1, No. 2, p.7–14, 1983 Retrieved on 2011-01-11

Wikipedia Source

This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page.

carbonate-minerals halide-minerals lead-minerals luminescent-minerals minerals-in-space-group-127 tetragonal-minerals

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