Smithsonian Report. 1963. — Gettens 



Plate 5 



The detail, upper (magnification c. 15X), taken from the stem of the old Persian lamp 

 (plate 4, opposite) shows colorless crystals of phosgenite which is a double salt of lead 

 carbonate and lead chloride. The larger phosgenite crystals are intermingled with 

 smaller dark blue crystals of the rare mineral cumengite shown in the detail, lower (c. 15X). 

 Cumengite is a complex basic salt of lead and copper chlorides. Freer Gallery of Art. 



