A few words on Purbeck Marble

Today's research snippet.
Purbeck Marble - in brief

Purbeck columns at the Temple Church

Purbeck marble was a highly prized building material in the 11th through to 16th centuries, with its heyday in the 12th and 13th.
It can only be obtained from one place and that's land in the area of Corfe on the Isle of Purbeck in south-eastern Dorset.  It's not a marble technically speaking, but actually a polishable limestone and his characterised by tightly packed fossil shells of the water snail viviparus carinfer.  It comes in a variety of shades including blue-grey, red-brown and green.  The vein of this limestone is between 18 and 24 inches thick and was worked from the surface.
Thousands of architectural objects have been fashioned by Purbeck  stone, including columns at the Temple Church, William Marshal's effigy, and a magnificent fountain that used to stand outside the private apartments at the palace of Westminster.  Henry of Blois, Bishop of Winchester and brother to King Stephen, used Purbeck for wall shafts, capitals and bases at Wolvesey Palace in the mid 12thc and also for elaborate colonnettes at Hyde Abbey.
Working the marble is tricky because of its denseness and required expert workers in the craft.  Such craftsmen worked in the Purbeck area itself, and in London.
One of the reasons for the success of Purbeck was the coastal location which made transportation easy.  Columns were shipped up to Durham Cathedral in 1175.  Capitals and bases went to Norwich, to Westminster, to Vale Royal.  In 1375, a ship called The Margarite out of Wareham was listed as transporting cargoes of Purbeck to London, including two high tombs for the Earl of Arundel and a large slab for the Bishop of Winchester.  In 1386 the same ship took Purbeck from Dorset to London intended for the tomb of Edward III.

Tomb of King John: Worcester cathedral

The London crafstmen originally came from Corfe but settled in their own community in the capital.  The biggest influx seems to have come with the requirement for building and beautifying at Westminster Abbey instigated by Henry III in 1245.  By 1253 there were 49 marblers on the site all cutting and polishing the marble blocks and shafts.  There were probably also centres of marbling at other great ecclesiastical sites - Salisbury cathedral for example, which was sending worked marble to Southampton in 1231-2.
The most successful Purbeck items for the mass market in its 12th and 13thc must-have period were tomb slabs and effigies. William Marshal as aforementioned, Henry Bishop of Winchester, King John, Hubert Walter, Archbishop of Canterbury.
Later on, Purbeck continued to be in high demand when funeral brass effigies became the rage, and the marble was used as the background slab.  It was still also being  used for panelled tomb chests and large, canopied wall tombs.
Today it's no longer quarried on the former sites except for specialist projects such as restoration.