Crystallography of Lanarkite

Lanarkite, Pb₂SO₅, has been found in measurable monoclinic crystals only from the Susanna Mine, Leadhills, Lanarkshire, Scotland (Heddle, 1901). The only complete description of these crystals was given by Schrauf (1877), who chose pseudorectangular axes (β = 91°49′)- Goldschmidt chose a setting with the axes considerably inclined (β= 119°23′). Specimens in the Harvard collection from the type locality were examined by Richmond in connection with other work; these proved to be a rich source of new data. X-ray investigation revealed that neither the Schrauf nor the Goldschmidt settings were in agreement with that of the simplest structural cell.