The geological and historical milieu of an ornamental cephalopod limestone (‘orthoceratite limestone’, Ordovician, Sweden) used in the Clerk Mausoleum (1684), St Mungo's Kirkyard, Penicuik, Scotland

A slab of cephalopod limestone bears a dedicatory Latin inscription on the mausoleum built around 1684 by Sir John Clerk of Penicuik (1649–1722) for his wife Elizabeth Henderson (1658–83) at St Mungo's Church, Penicuik, near Edinburgh, Scotland. The stone is identified on sedimentological and palaeontological evidence and historical context as Ordovician ‘orthoceratite limestone’ from Sweden, probably the island of Öland, rather than Carboniferous cephalopod limestone from the much nearer Closeburn area of Dumfriesshire. ‘Orthoceratite limestone’ was little used in Great Britain, and mainly as paving, so its use in a funerary monument is unusual. It is, however, paralleled by contemporary examples at Winchester Cathedral. The Penicuik slab was probably imported either directly from Sweden, or through Rotterdam or another Netherlands entrepôt. It is the only surviving historical example of this stone known in Edinburgh and the Lothians, probably because of changing fashions, building demolition and renewal of worn paving. The inscription shows errors of composition, carving and installation, ascribed to inexperience or haste. The employment of ‘orthoceratite limestone’ is interpreted as seeking to emulate Roman use of marbles and similar ornamental stones. It contributes to the Penicuik mausoleum's significance as a pioneering example of classical or Antique architecture.