First discovered over two thousand years ago by the Romans, Blue John is an unusual mineral from the area around Mam Tor mountain at Treak Cliff near Castleton in Derbyshire, England (figure 2). This is the only known location where Blue John can be found, though other types of fluorspars are mined throughout the world. The name “Blue John” is believed to derive from the French bleu jaune,1 meaning “blue-yellow,” and it is characterized by bands of blue/purple and yellow/white colored veins. It is a difficult material to work with, as the stone is soft, brittle, and can be altered in coloration by excessive heating.2 Because of its rarity, the material is no longer used on a grand scale. Presently, only approximately one quarter of a ton is excavated each year and is used primarily for jewelry and small objects.
Blue John was first used by the ancient Romans and then again beginning around 1760. In late 18th century England, local industry centered around the production of decorative objects in Blue John such as vases, obelisks, and mantel garnitures. These were sometimes embellished with gilt-bronze mounts (figure 3). One of the most proficient users of the stone was Matthew Boulton. He worked extensively in Derbyshire marbles and fluorspars to produce a variety of decorative objects like urns, cassolettes, and perfume burners. Boulton’s technical virtuosity is seen in both the sculpting and application of gilt-bronze mounts to the delicate stone.
Blue John was used to furnish the finest British houses, notably Chatsworth, home of the Duke and Duchess of Devonshire, and Kedleston Hall, where it was first employed by Robert Adam. A chimneypiece designed by Adam and made by Joseph Hall or Derby was installed in the Kedleston Music Room in 1761 (figure 4). It is the earliest recoded use of Blue John in the applied arts.
In the Carlton Hobbs collection, a pair of blue john decorations are distinguished by their large scale and fine regular veining (figure 1). They were almost certainly employed as ornaments for the shelf of a fine neoclassical chimney piece.