Hopton Wood stone
Hopton Wood Stone (sometimes Hopton-Wood Stone or Hoptonwood Stone) is a type of limestone quarried north of Hopton and west of Middleton-by-Wirksworth, Derbyshire, England.
Developed first by the Gell family, and then by The Hopton-Wood Stone Firms Ltd, it was called "England’s premier decorative stone", and described as "remarkably and exceptionally pure limestone, almost identical to marble" with impurities at an "extraordinarily low figure of 0.02%".