About this image
Tufa Cottage was built around 1830 as a gamekeeper's cottage for the Gell Estate. Constructed from tufa it is said to be the only house in the UK built from this rock. Only found in a limited number of locations in the UK, tufa is calcified moss that has grown on volcanic lava. On some of the early photographs that follow, the source of the rock can be seen behind the house. Appearing in many guide and history books and also on TV in The Heart of the Country, Tufa Cottage is a well known landmark even if you ignore the appearance in Haunted Houses of Derbyshire!
(taken from http://www.tufacottage.com/)