A distinctive type of pottery produced in Derbyshire from the mid 2nd century ad through to the 4th century ad. It is hard and gritty with a surface that is sometimes described as being like ‘petrified gooseflesh’. Colour varies from grey and light‐brown to red. The surface texture is due to the presence of silica particles in the local clay. All vessels are jars, mostly with a lid‐seating on the rim.