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Phosgenite
Current inventory:  2 gems
 

Chemistry:  Pb₂(CO₃)Cl₂  [Lead Carbonate Chloride]

Discovered in 1841;   IMA status: Valid (pre-IMA; Grandfathered).
The name Phosgenite comes from phosgen, a name for carbonyl dichloride, COCl₂, because the mineral contains carbon, oxygen, and chlorine.

Classification

Mineral Classification:

Carbonates

Strunz 8th Ed. ID:

5/C.09-10

Nickel-Strunz 10th Ed. ID:

5.BE.20

5 : CARBONATES (NITRATES)
B : Carbonates with additional anions, without H₂O
E : With Pb, Bi

Related to:

Phosgenite - Beyerite Series

Crystal Data

Crystallography:

Tetragonal - Ditetragonal Dipyramidal

Crystal Habit:

Crystals are short prismatic; rarely thick tabular; commonly terminated to 30 cm; granular, massive.

Twinning:

None

Physical Properties

Cleavage:

[110] Good, [001] Good, [010] Indistinct

Fracture:

Conchoidal

Tenacity:

Sectile, Flexible - Curved shavings or scrapings

Moh's Hardness:

2.0 - 3.0 (varying with direction)

Density:

6.12 - 6.15 (g/cm³)

Luminescence:

Weakly Fluorescent; may fluoresce Yellow under LW & SW UV, X-rays and cathode rays

Radioactivity:

Not Radioactive

Other:

Decomposes slowly in cold water, which extracts lead chloride.

Health Warning:

CAUTION: Contains Lead. Wash hands after handling. Do not lick or ingest; do not inhale dust when breaking. Do not grind dry.

Optical Properties

Color:

Pale yellow to yellowish brown, pale brown, smoky brown, smoky violet; colorless, pale rose, gray, yellowish gray, pale green

Transparency:

Transparent to Translucent

Luster:

Adamantine

Refractive Index:

2.118 - 2.145  Uniaxial ( + )

Birefringence:

0.0270

Dispersion:

None

Pleochroism:

Very weakly pleochroic; O = reddish pink and E = pale green in thick sections

Occurances

Geological Setting:

Uncommon, typically formed by alteration of galena in the oxidized zone of hydrothermal lead deposits, or by reaction of sea water with other lead minerals.

Common Associations:

Anglesite, Cerussite

Type Locality:

n/a

Year Discovered:

1841

View mineral photos:

Phosgenite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Phosgenite is a very rare gem that is very soft and fluoresceses yellow under long wave UV light. It is very attractive in several colors and has a high refractive index. Facetable crystals are only found in a couple locations; Sardinia, Italy and Tsumeb, Namibia.
 

  
Phosgenite gems for sale: