The fabric of Southwell Minster is dominated by stone originating from within the Late Permian Cadeby Formation (the former 'Lower Magnesian Limestone'). The stone came from quarries in the neighbourhood of Mansfield and Mansfield Woodhouse, twelve or fourteen miles away through Sherwood Forest, although there have been suggestions that Bolsover (where the Cadeby Formation was also quarried) could have been an additional source.  

The lithological characteristics of the Cadeby Formation vary quite dramatically along the length of its outcrop (which stretches from north Nottinghamshire to County Durham). Although by no means as dramatic as the unit as a whole, the nature of the Cadeby Formation does vary in the Mansfield area; the detrital quartz (and feldspar) content is highly variable (being small, moderate or substantial), such that the beds variably consist of slightly to significantly sandy dolostone or dolomitic sandstone. An examination of some of the blocks of Southwell Minster with a hand lens shows that the detrital sand/silt content is indeed rather variable.

It is also worth noting that Middle Jurassic Lincolnshire Limestone was used for modifications to the Chapter House passage 1429-30. Jennifer Alexander's 1995 paper in Medieval Archaeology contains the following: Stone from Heselburgh, in Heydour parish, to the SE of Ancaster, was used at Southwell Minster for work in the Chapter House and its vestibule, although the main walling stone that had been used for the building was Mansfield and stone roof tiles from Mansfield were used for roofing the new work. The work in question involved: removing the vaulted stone ceiling which dated from c1200-1300; increasing the height of the east wall of the passage and incorporating eight small double-light windows above the string-course; increasing the height of the west wall; and replacing the vault with a stone roof of very low pitch, to incorporate a timber ceiling. Fragmentary fabric accounts from that period appear to name 'Peter de Hassilbargh' as the master mason for the work, leading to the conclusion that he insisted on stone from his home territory.

The stone used by the Norman builders is of a dark yellowish hue, while their Early English and Decorated successors found some of a lighter hue with blue-tinted veins. Since all the stone used to build and to repair the fabric of the minster (with the exception noted above) has come from the same Formation, but not always from the same quarry, it is probable that the slight variations in appearance between the stone of the nave (completed c1160), the Early English choir (completed c1250), the chapter house and its passage (completed c1300) and the pulpitum (completed c1340) are due to the different sourcing.

The minster was fortunate in the choice of material and has always been envied. That eminent geologist Sir Roderick Murchison once expressed his regret that, when the Houses of Parliament were rebuilt, the Mansfield quarries were not used. 'If Mansfield stone had been used', he wrote, 'not one pinnacle in that otherwise grand building would have been caused to perish.' There is no fear of the Minster perishing. Nave and transepts have already withstood the storms and rains of nine hundred years, and choir and chapter house for almost as long.