What is "phosgenite"

Phosgenite \Phos"gen*ite\, n. (Min.) A rare mineral occurring in tetragonal crystals of a white, yellow, or grayish color and adamantine luster. It is a chlorocarbonate of lead.

n. (context mineralogy English) A tetragonal-ditetragonal dipyramidal mineral containing carbon, chlorine, lead, and oxygen.

Phosgenite is a rare mineral consisting of lead chlorocarbonate, (PbCl)CO. 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.