Phosgenite: Gemstone Information
Phosgenite is Pb2(CO3)Cl2 and forms transparent to translucent colourless short prismatic to prismatic crystals of the tetragonal system with adamantine lustre, hardness 2–3 and SG 6.12. The RI for the ordinary and extraordinary rays is 2.118 and 2.145 m, uniaxial positive, anomalously biaxial, birefringence 0.028. A pronounced yellow fluorescence can be seen under UV and X-rays.Phosgenite occurs from the alteration of galena in the oxidized zone of lead ore deposits. Fine crystals are found in the Monteponi and Montevecchio areas. Fine crystals are also found at Tsumeb, Namibia,and there are occurrences in Namibia, Morocco and Tasmania.