Details

The monument includes the northern part of the Prince of Wales Mine which is
situated on a gentle south facing slope on the northern edge of Harrowbarrow
village.

The mine represents an amalgamation of several other mines amongst which are
Wheal Fortune, Wheal Pleasant, Wheal George, Wheal Barnard and West Edward
which together were known as Calstock United Tin and Copper Mines in the
early part of the 19th century. In 1861 the mine was re-constituted as the
Prince of Wales Mine and operated intermittently from then until 1914. In
1940, during World War II, a processing floor was established at the mine to
rework the earlier dumps and material from nearby small mines and Devon Great
Consols. In about 1971 a Canadian company carried out exploratory work
including drilling and finally in 1977 an exploratory adit was cut into the
hillside. Between 1861 and 1914 output from the mine was 10,845 tons of
copper ore, over 1000 tons of black tin and 7,720 tons of arsenic yielding
iron pyrites.

The mine's relatively long and productive life has resulted in a complex
series of structures and earthworks surviving. Amongst these are three
engine houses, shafts, a dry, at least two processing floors of different
dates, a magazine, two boiler ponds, tramways, concrete buildings and
extensive waste dumps. All three engine houses were constructed with
pinkish shillety killas, with wooden lintels and without granite quoining.
The western engine house was built in 1888 and powered stamping machinery.
It was modified during the 1940's reprocessing event and at this time the
stamping floor, loading and boiler house were demolished. The middle engine
house, built in 1879, once held a 50 inch pumping engine extracting water
from the adjacent Watson's Shaft and its boiler house is attached to its
eastern wall. Its detached chimney, which is capped with brick and
incorporates a decorative drip-ring and cap, stands a short distance to the
north west and they are connected to each other by an underground flue. The
third engine house, installed in 1888, held an all-indoor beamed rotative
engine for winding from Watson's Shaft. The bedstone remains in its original
position and to the south is the crankshaft loading and a rectangular pit
which would have held the winch drum. Traces of the boiler house survive to
the north. The dry building stands to the north of the pumping engine
house and was enlarged to incorporate its chimney sometime between 1881 and
1906. In this building miners' wet clothing was dried, presumably using
heat generated by a flue from the nearby boiler house. Much of the earlier
tin dressing floor now underlies later waste material, although three conical
buddles protruding through this material indicates that much of this floor,
which was housed in a large building, survives as a buried feature. By
contrast much of the 1940's dressing floor survives as a series of concrete
footings and bases together with a large ore bin.

A small stone-built standing structure set away from the mine at NGR SX
39957059 may represent the site of a powder magazine. Two boiler ponds are
known from early maps. The first at NGR SX 40027058 has been truncated by
the 1977 adit, whilst the other larger example at NGR SX 40107063 survives as
a rectangular water filled hollow denoted on its lower side by a substantial
bank. A small number of concrete buildings surviving within the monument
relate to the 1940's reworking, whilst a large adit together with tramways
belong to the 1977 exploration. Dominating the southern part of the monument
are substantial dumps of fine yellow-grey sand. These represent waste from
the 1940's activity, but they do overlie and protect earlier dumps.

Modern fences built around open shafts and other structures are excluded from
the scheduling, but the ground beneath them is included.

MAP EXTRACT
The site of the monument is shown on the attached map extract.

Source: Historic England

Reasons for Scheduling

For several millennia the western part of the South West Peninsula, namely
Cornwall and West Devon, has been one of the major areas of non-ferrous
metal mining in England. It is defined here as prospecting, extraction,
ore processing and primary smelting/refining, and its more important and
prolific products include copper, tin and arsenic, along with a range of
other materials which occur in the same ore bodies. Throughout much of the
medieval period most of the tin was extracted from streamworks, whilst the
other minerals were derived from relatively shallow openworks or shafts.
Geographically, Dartmoor was at the peak of its importance in this early
period.
During the post-medieval period, with the depletion of surface deposits,
streamworking gradually gave way to shaft mining as the companion to
openworking methods. Whilst mining technology itself altered little, there
were major advances in ore processing and smelting technologies. The 18th
century saw technological advances turning to the mining operations
themselves. During this period, Cornish-mined copper dominated the market,
although it was by then sent out of the region for smelting. The
development of steam power for pumping, winding and ore processing in the
earlier 19th century saw a rapid increase in scale and depth of mine
shafts. As the shallower copper-bearing ores became exhausted, so the mid
to late 19th century saw the flourish of tin mining operations, resulting
in the characteristic West Cornish mining complex of engine houses and
associated structures which is so clearly identifiable around the world.
Correspondingly, ore processing increased in scale, resulting in extensive
dressing floors and mills by late in the 19th century. Technological
innovation is especially characteristic of both mining and processing
towards the end of the century. In West Cornwall, these innovations relate
chiefly to tin production, in East Cornwall and West Devon to copper.
Arsenic extraction also evolved rapidly during the 19th century, adding a
further range of distinctive processing and refining components at some
mines; the South West became the world's main producer in the late 19th
century.
From the 1860s, the South West mining industries began to decline due to
competition with cheaper sources of copper and tin ore from overseas,
leading to a major economic collapse and widespread mine closures in the
1880s, although limited ore-extraction and spoil reprocessing continued
into the 20th century.
A sample of the better preserved sites, illustrating the technological and
chronological range, as well as regional variations, of non-ferrous metal
mining and processing sites, together with rare individual component
features, are considered to merit protection.

The northern part of the Prince of Wales Mine at Harrowbarrow survives well
and contains an extensive range of structures associated with a late 19th
century tin mine. The dumps in particular form a prominent local landmark and
will contain information concerning the character and efficiency of tin
extraction. The mine has a long history and much of it is represented by the
surviving structures.

Source: Historic England

Sources

Books and journals
Sharpe, A, Duchy of Cornwall Industrial Sites: A Survey, (1989), 10-22

Source: Historic England