Phosgenite

Phosgenite Monteponi Mine, Iglesias, Province of Carbonia-Iglesias, Sardinia, Italy Specimen weight:155 gr. Crystal size:2,8 cm Overall size:5,5 x 3 x 3,5 cm © minservice
Chemical Formula: Pb2CO3Cl2
Name Origin: Named from the composition phosgene (COCl2), as the mineral contains this compound.Phosgenite is a rare mineral consisting of lead chlorocarbonate, Pb2CO3Cl2. 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

The name phosgenite was given by August Breithaupt in 1820, from 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 Rosalia, Baja California. 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 Pb2Br2CO3, have been prepared artificially.

History

Discovery date : 1800

Optical properties

Optical and misc. Properties : Luminescent, fluorescent  –   Transparent  –   Translucide  –   Gemme, pierre fine
Refractive Index: from 2,11 to 2,14

Physical properties

Hardness : from 2,00 to 3,00
Density : 6,13
Color: colorless; white; yellowish white; grey; brown; greenish; pinkish; pale brown
Luster : adamantine; vitreous; greasy; waxy
Streak: white
Break : conchoidal
Cleavage: Yes

Photos:

Phosgenite Monteponi mine – Iglesias – Carbonia-Iglesias prov. – Sardinia – Italy Specimen weight:850 gr. Crystal size:mm. 17 x 14 x 12 Overall size: 85mm x 45 mm x 70 mm © minservice
Phosgenite Monteponi Mine, Iglesias, Province of Carbonia-Iglesias, Sardinia, Italy Specimen weight:25 gr. Crystal size:2,5 cm Overall size: 29mm x 22 mm x 15 mm © minservice
Phosgenite Monteponi Mine, Iglesias, Carbonia-Iglesias, Sardegna  Italy (1989-1992) Specimen size: 5.6 × 4.4 × 1.8 cm = 2.2” × 1.7” × 0.7” Main crystal size: 5.2 × 4 cm = 2.0” × 1.6” © Fabre Minerals
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