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. Pauls 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 supposed 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".
George Head describes the working of this small quarry in 1832:
Then proceeding a few hundred yards along the beach, I dismounted, fastened my animals 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. Pauls Cathedral. Nothing more was now to be observed on the spot than a temporary masons 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 masons tools lay scattered about the hut, but within and without there were no other preparations for labour, not even a common crane.
James McCrone (Crown Agent) in a letter to London dated 31 Oct 1836 [Letter Book 2 MS 01981C] states he as been asked by Mr Joseph Greenwood of Clement St SawnMill, Liverpool for a lease on the Polvash marble quarries and the Lime quarries at Scarlet - "the marble quarries have been wrought by native jobbers for the use of the Island and they have not paid any Lordship, but as the consumption is now considerable Mr Greenwood has it in view to work them extensively for home demand and for exportation to England ... The Manks Marble does not polish fine, but nevertheless it makes very good Chimney pieces and for monumental purposes - the steps of the church of St Pauls are made of it".
Eva Wilson covers the story of the supposed gift of Bishop Wilson - it would appear that black marble from Poolvash was used in the in the aisles of the new church of St Peters in Liverpool which was consecrated in 1704; the accounts of St Pauls describe their black marble as Black Irish Marble which very likely came from a quarry near Dublin. The use of the Manx black marble in Liverpool may well have publicised the availability of the material outside of the Island as in 1705 some 1058ft of flags were sent to London for William Holland, a master mason who had previously supplied some Swedish marble to St Pauls. Manx born Thomas Allen and Wm Pinder came to the Island in 1713 with letters of credit to supply their old masters Edward Stanton and Wm Holland with tombstones and flags. Allen stayed on Island having married Hannah Reece - Wilson found other shipments of stone by him back to London before following his wife's death Allen left to return to London in 1724. It would seem that the use in St Peters and the later purchase by one of the firms of Masons who had earlier supplied St Pauls were conflated into the supposed gift by Bishop Wilson - this story according to Eva Wilson first appeared in Townley's Journal of 1789/90.
However there is now some Poolvash marble in St Pauls, as following the restoration of the steps in 1873 which used Guernsey dark granite, some Poolvash marble was bought to renovate the North Portico which originally had used the Irish black marble for which it appears the Manx stone was a good match.
Eva Wilson Bishop Wilson and the Steps of St Pauls Proc IoM Natural History and Antiquarian Society Vol XII #1 pp 133/146 2008