The most complete remaining building of the Serpentine factory is a traditional, stone rubble building, three storeys high, with a gabled front, an opening on each floor and a slate roof. It is at the seaward end of the range of buildings and is dated 1866.
‘In the works, small ornaments in serpentine stone were being made in 1838. The firm evidently prospered for, about the years 1854 – 1889, the factory was producing mantelpieces, shop fronts, ornamental urns, etc. on a large scale (Lizard Field Club, Poltesco Cadgwith Nature Trail).
The wheel pit (90586*0) for a 25-foot diameter water wheel is still visible at the landward end of this range of buildings. The wheel would have worked machinery for the sawing up of the serpentine; and near the stream is a large slab of stone, scored by saw marks.
‘The finished articles were shipped from Penrhyn and Falmouth. Slabs of serpentine cut here were used in the Duchy of Cornwall buildings in London, and the firm had showrooms near the Strand where a vase 7’6″ high was to be seen (Lizard Field Club, Poltesco Cadgwith Nature Trail) (National Trust 1986).
Gabled three-storey rectangular stone warehouse, built into rising ground so top floor opens at ground level on the rear. The front elevation has a large doorway to each floor and datestone LSCL 1866 in gable apex. The warehouse is the remnant of a once much larger factory complex whose ruins can be seen on the left. Adjacent on the right is Rouds C18 capstan house of irregular rubblestone and now roofless (possibly originally thatched). Blocked opening for hauling rope/cable on the seaward face. Interesting for demonstrating changing industrial activities, i.e. Pilchard fishing and pressing, here followed by quarrying, polishing and processing of serpentine stone. Both industries once enjoyed prosperity but have now vanished with the production of tourist memorabilia being the only reminder of former times.

From Preliminary Archaeological and Historical Survey – Poltesco Valley, 2003, and according to which this factory is not Listed:-
The Poltesco serpentine factory was established in c1855 and ceased operations in c1893. It manufactured items such as church fonts, fireplaces, shop fronts and other decorative items. A late 19th-century photograph shows that the serpentine factory comprised two machine shops aligned east-west with gabled roofs, 92535 and 92536, two north-south aligned buildings with hipped roofs possibly a store 92534 the offices and showroom, 92528, and three storey warehouse with a gabled roof, 92527. To the north of the main complex was the forge, a two-storeyed building with a gabled roof, 92537.

Power for cutting, turning and polishing the stone was originally supplied by a large overshot waterwheel in the wheel pit, site 90856, which was fed by a long wooden launder, 92542, crossing high above the Poltesco stream carrying water from the ponds further up the valley, 92543 and 92544, supplied by a leat, 92545, from the dam in the river, 92546. The Trust is considering the provision of a hydroelectric turbine for the occasional supply of power to the buildings at Poltesco, which will re-use the existing ponds and watercourses. The proposal would involve piping water from the leats through the sluice gate of the lower pond to a hydro-electric turbine discreetly sited at the river bank approximately adjacent to the foundation stone of the former aqueduct, giving c6.500m head of water (Liddicoat 2000).

Steam power was introduced in 1866 and there are the remains of a boiler house, 92532, and a demolished chimney stack, 92531, and engine room, 92530, at the centre of the factory range. Whether steam power supplemented or replaced water power is not known. It was probably used for the heavier operations, sawing and surfacing while the water wheel powered the lathes. In front of the factory range is a stone saw block, where the stone was cut using a toothless saw, site 92533.

An aquatint from ‘The Illustrated London News’ (Fig 27), shows an impressive wooden gantry, site 92540, with a rail-mounted truck used for transporting stone from a platform, site 92541, on the far side of the stream with a chute, probably into the yard, site 92529, behind the office/showroom, site 92528. A travelling crane mounted on the quay, site 92538, may also have been used for this purpose.

The serpentine factory is last mentioned in Kelly’s Directory of 1893 when the manager was John Nankerris of Ruan Minor. The factory is marked as ‘Carleon Factory (Serpentine)’ on the 1879 OS map and ‘Carleon Factory (Disused)’ on the 1907 OS map (Fig 19).

The serpentine factory was mostly demolished by Mr Ironside in the 1930s after a survey for the Council for Protection of Rural England (CPRE) recommended that they were ideal for conversion to holiday homes (Unwin 1974; M Hardy pers comm).