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拍品專文
Blue-John is a natural coloured veined fluorspar only found at Treak Cliff, near Castleton in Derbyshire. The radiating crystalline structure contains bands of blue and purple intersected with other bands of varying colours. It is believed to have been first mined by the Romans, with two vases having been excavated at Pompeii. However, its use for ornamental purposes occurred in the second half of the eighteenth century when it was fashioned into decorative objects and used for architectural purposes in decorative schemes.