Collyweston stone slate

Collyweston stone slate is a traditional roofing material found in east-central England, primarily in Northamptonshire, Cambridgeshire, Lincolnshire, and Rutland.

The slates are quarried near the village of Collyweston in Northamptonshire, near Stamford and close to the borders of Lincolnshire and Rutland.

Traditionally the mined stone was left outside for three winters until the frost revealed layers that could be broken ("clived") into flat slates.

In the late 1990s, English Heritage (now Historic England) worked with the Burghley Estate and Sheffield Hallam University to develop an artificial system to reproduce the freeze-thaw cycle needed for production of slates.

New slates have been used to repair the roofs of Ufford Church in Cambridgeshire and High Wycombe Guildhall.