A rare monoclinic lead sulphate carbonate hydroxide, polymorphous withsusannite (Trigonal) andmacphersonite (Orthorhombic). Typically these minerals are all found as small to microscopic clear to white tabular pseudohexagonal crystals (trillings for leadhillite).
Heating leadhillite causes it to reversibly transform into susannite in the temperature range from 50 to 82°C (Bindi & Menchetti 2005).