The Stanley Grange Medieval Iron Project
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Patrice de Rijk, Research Associate
In 1997, an area of c. 1.5 ha associated with medieval iron smelting was investigated by Trent and Peak Archaeology at Stanley Grange, Derbyshire, UK. Excavation recovered the remains of at least eight furnaces, ore crushing areas and deposits of smelting slag, as well as features possibly related to the forging of the iron produced (bloom smithing). The furnaces have been dated by archaeomagnetic techniques to the 13th or 15th century AD, but only the earlier date is supported by artefacts, principally medieval ceramics.
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Stanley Grange is one of only a handful of medieval iron smelting sites known from excavation within Britain and is contemporary with the rapid and dynamic technological developments that characterised European iron smelting between the 11th and 14th centuries. In this period a gradual transition took place from the direct production of iron in low shaft furnaces or “bloomeries” to the indirect production iron in blast furnaces. The terms direct and indirect refer to the subsequent treatment of the produced iron: in a bloomery malleable iron is won in a solid state extraction process, in a blast furnace fluid cast iron is produced that has to be decarburized in a subsequent fining process to make it malleable. Such technological developments had a significant impact on European society and economy.
The objectives of the Stanley Grange medieval iron project incorporate two broad components: a full understanding of the technological basis of the iron production at Stanley Grange, and a contextualisation of this evidence within our current archaeological, historical, cultural and environmental understanding of medieval Britain.
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Figures
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Figure 2. The remains of iron smelting furnace no. 137 at Stanley Grange.
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Figure 3. A furnace slag from the slag tapping pit of furnace no. 77.
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Figure 4. A reflected light microscope image of dense tap slag from furnace 100, showing fayalite laths (mid-grey) with wustite dendrites (white) in a glassy matrix (dark grey).
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Figure 5. An electron microprobe image of slag sample SGD-162-149, showing wustite dendrites (light grey) in a glassy matrix (mid-grey) and metallic iron (small white inclusion near middle of image).