Furnace

The National Monuments Service's description

The results of archaeological monitoring of topsoil removal in Kilfinnane was summarised as follows; 'Topsoil-stripping under licence No. 06E1221 by Headland Archaeology Ltd. took place in April 2007 of a proposed Limerick County Council housing development in Kilfinnane, Co. Limerick. Two archaeological features were identified: a subcircular smelting hearth/furnace, 1m long, 0.9m wide with a depth of 0.12m, and a shallow waste pit, which was oval-shaped in plan, 0.9m long, 0.5m wide, 0.1m deep. Prehistoric pottery was recovered from the fill of the later feature' (https://excavations.ie/report/2007/Limerick/0018093/).
According to Moloney (2007, 8-9); 'The burnt feature [1002] was likely to have been a smelting hearth or bloomery furnace due to the on‐site identification of a diagnostic piece of slag. The slag appeared to be adhered to burnt soil and was of a highly vitrious globular nature. The high remaining iron content of the other recovered pieces of slag, indicated by their weight, also suggested that the feature was part of the bloomery smelting process. Bloomery furnaces are often limited in the quantity of iron they can obtain from the ore and the slag produced often contains much more iron than the slag derived from a highly efficient process such as a blast furnace. Iron rich slags could also be the result of non‐tapping furnaces however and the recovered slag is unlikely to include a representation of tapping slag.
At first it would appear that a smithing hearth would be a more likely interpretation of the isolated feature but if the identification of the bloomery slag is correct and the slag is directly related to the use of the feature then it would suggest the single use of a pit to process ore. This was possibly to reduce the load of an itinerant smith who may also have utilised this method of smelting occasionally. The feature may, although not necessarily, have been located close to the source of ore, either mined iron ore or bog iron. If bog iron was used it is more likely that the furnace was of a nontapping construction. The large quantity of slag and small size of the hearth may suggest that the smelt was a failure and was abandoned. It could also be the case that the hearth had been heavily truncated'.

See attached location maps and photographs taken from excavation report by Headland Archaeology Ltd.

Compiled by: Caimin O'Brien

Date of upload: 5 April 2022

References

Moloney, C. 2007 Preliminary Report on Archaeological Monitoring of a Housing Development at Kilfinnane, Co. Limerick. Unpublished report. DEHLG (06E1221). Headland Archaeology for Limerick County Council.