B170 Black Marble

Commemorative Tablet at Castletown

A commonly described mineral product is the 'Black Marble' quarried at Poolvash [PooilVaaish] between Castletown and Port St Mary.

For the student of volcanic phenomena no finer display could be desired than is afforded by this strip of the Manx coastline, "for here he sees a small ancient volcano dissected and laid bare" (Lamplugh 1896)

Lamplugh in his Geology of the IoM give the following description:

The so-called ‘black marble’ of Poolvash was obtained from the harder courses in the black flaggy and shaly "Posidonomya Beds "on the eastern shore of Poyll Vaaish,.. but is not at present worked. The best stone seems to have been found immediately underlying the volcanic ash, where the rock has been indurated, probably by a slight over-thrust of the Volcanic Series. Among other uses, it was wrought into chimney-pieces, tombstones and steps. Being too soft to take a natural polish, it was covered with a kind of black varnish, and in this way objects wrought out of it were "made to look not much inferior to the best Derbyshire black marble." The tombstones made from it show rapid weathering. The "steps of St. Paul’s Cathedral in London," so often mentioned in Manx topographical literature as having been supplied from this locality, seem to be no longer in existence. The total extent of the ‘black marble’ quarrying has not been great.

The reference to the steps of St Paul's refers to a gift of Bishop Wilson of some of this marble to help in the rebuilding of St Pauls - in his History Wilson writes that the marble is "fit for tombstones, and for flagging of churches; of which some quantities have of late been sent to London for those uses". All these steps except the top one that ran under the columns of the west portico had been replaced by granite in the 1860's, with recovered marble used to patch this top step - however the current 2005 restoration has seen new stone cut to replace the badly worn step.

George Head describes the working of this small quarry in 1832:

Then proceeding a few hundred yards along the beach, I dismounted, fastened my animal’s bridle to a large stone, and walked seaward to the quarries. These consist of numerous small excavations, situated below high water-mark, filled with water at flood tide, and baled out previous to working every day, until the pit, becoming so large as to render the operation too laborious, is necessarily abandoned by the workmen, who then sink another. Reefs of remarkably black rock are abundant at this part of the coast ; they extend considerably high upon the beach, although the pure marble, as already stated, all lies low ; indeed a stranger might readily pass the spot, and unless the quarries were brought to his notice, fail to perceive them. They have been worked nevertheless many years, and actually furnished a part of the material for the building of St. Paul’s Cathedral. Nothing more was now to be observed on the spot than a temporary mason’s hut, surrounded by a few slabs for chimney-pieces and grave-stones, in progress of manufacture ; the marble of which, of a rich black and shining quality, was already fashioned and polished. A few ordinary mason’s tools lay scattered about the hut, but within and without there were no other preparations for labour, not even a common crane.