Reasons for Designation
Approximately 10,000 lead industry sites are estimated to survive in England,
spanning nearly three millennia of mining history from the later Bronze Age
(c.1000 BC) until the present day, though before the Roman period it is likely
to have been on a small scale. Two hundred and fifty one lead industry sites,
representing approximately 2.5% of the estimated national archaeological
resource for the industry, have been identified as being of national
importance. This selection of nationally important monuments, compiled and
assessed through a comprehensive survey of the lead industry, is designed to
represent the industry's chronological depth, technological breadth and
regional diversity.
Ore hearth smelt mills were introduced in the 16th century and continued to
develop until the late 19th century. They were the normal type of lead smelter
until the 18th century, when they were partially replaced by the reverberatory
smelt mill. The ore hearth itself consisted of a low open hearth, in which
lead ore was mixed with fuel (initially dried wood, later a mixture of peat
and coal). An air blast was supplied by bellows, normally operated by a
waterwheel; more sophisticated arrangements were used at some 19th century
sites. The slags from the ore hearth still contained some lead. This was
extracted by resmelting the slags at a higher temperature using charcoal or
(later) coke fuel, normally in a separate slag hearth. This was typically
within the ore hearth smelt mill, though separate slag mills are known.
Early sites were typically small and simple buildings with one or two hearths,
whereas late 18th and 19th century smelt mills were often large complexes
containing several ore and slag hearths, roasting furnaces for preparing the
ore, refining furnaces for extracting silver from the lead by a process known
as cupellation, and reducing furnaces for recovering lead from the residue or
litharge produced by cupellation, together with sometimes complex systems of
flues, condensers and chimneys for recovering lead from the fumes given off by
the various hearths and furnaces. The ore hearth smelt mill site will also
contain fuel stores and other ancillary buildings.
Ore hearth smelt mills have existed in and near all the lead mining fields of
England, though late 18th and 19th century examples were virtually confined to
the Pennines from Yorkshire northwards (and surviving evidence is strongly
concentrated in North Yorkshire). It is believed that several hundred examples
existed nationally. The sample identified as meriting protection includes: all
sites with surviving evidence of hearths; sites with intact slag tips of
importance for understanding the development of smelting technology; all 16th-
17th century sites with appreciable standing structural remains; 16th-17th
century sites with well preserved earthwork remains; and a more selective
sample of 18th and 19th century sites to include the best surviving evidence
for smelt mill structures, and flue/condenser/chimney systems.
Rookhope Old Smeltmill was abandoned in the late 1730s, and the area has been
little disturbed since. The earthwork remains are well preserved, and will
retain important technological information relating to the early 18th century
lead smelting. The earthwork remains include the smeltmill itself which will
retain evidence of the arrangements of the hearths, bellows and waterwheel.
The deposits of slag and ore processing wastes will provide additional
technological information, and the other surrounding earthworks, including the
remains of the small building to the south west, will contribute to the
understanding of the layout and operation of the site.
Details
The monument is situated on an abandoned river terrace beside Rookhope Burn,
630m north west of Lintzgarth Plantation. It includes the earthworks of a
small ore hearth smeltmill and its associated wheelpit, together with buried
deposits and other earthworks of an early ore processing area. The monument is
set within an extensive mining landscape with origins dating back to at least
the medieval period. Originally mined principally for lead, it was also worked
for other non-ferous minerals and iron ore from the 19th century. The valley
still retains an active fluorspar mine.
The mineral rights were held by the Bishops of Durham from 1154; they
appointed agents to grant mining leases and oversee the collection of the
Bishop's dues. In 1696, Sir William Blackett became the Bishop's agent and
formed the Blackett Company which dramatically changed the pattern of mining
within Weardale. The numerous small mining partnerships, each holding
individual leases from the agent, were replaced by a single mining company
holding a lease covering the whole area. It is thought that Rookhope Old
Smeltmill was built by this company around 1700, to smelt the valley's lead
ore. The Blackett company greatly increased the scale of mining within
Weardale in the early 18th century and built a second, larger smeltmill 1km to
the east shortly before 1740. Rookhope Old Smeltmill was abandoned in favour
of this new, more efficient mill in the late 1730s.
The smeltmill survives as a set of 0.5m high earthworks measuring c.15m
east-west and c.9m north-south. Interpreted as a three celled building with an
internal waterwheel on the south side, it is thought to have been powered by
water taken from Scar Sike. Set against the upper bank of the river terrace,
c.25m to the south west, are the ruined remains of a small 3m by 5m building
standing up to 0.75m high. Crossing the monument west to east, c.3m south of
the smeltmill, is a leat which runs from a 2m high dam immediately west of the
area of protection, to the site of Rookhope New Smeltmill, 1km to the east.
Part of this leat reuses the tailrace from the Old Smeltmill. All around the
mill are earthwork remains of other features, deposits of ore processing
wastes and smelting slag. These earthworks, typically standing to 0.1m-0.3m
high are thought to include the remains of manual ore processing areas where
the lead ore from the mines was concentrated before it was smelted.
MAP EXTRACT
The site of the monument is shown on the attached map extract.
