Cast Iron-Making at Letterewe:
17th Century AD
Among Scotland's charcoal operated blast furnaces, Letterewe, Loch Marie, Wester Ross, may be the earliest (early 1600's, but dates are still pending). Originally thought of as a High bloomery (essentially a tall shaft furnace operated by water power), Letterewe has now produced irrefutable evidence of being a blast furnace, both on account of its design as well as the waste products (blast furnace slag). Letterewe was home to Sir George Hay, an entrepreneur and also High Chancellor of Scotland, who acquired the monopoly for making iron and glass from James VI. With ore brought over from Fife but ample woodlands for his charcoal operated furnaces he set up, the manufacturing of iron. However, his operation was rather short lived. Manganese-rich bloomery slag, from the many bloomeries known to have operated on the south shore of Loch Marie appears to have been recycled as "ore", on account of its high iron content, but also as a means of de-sulphurising the metal by combining with sulphur (see manganese-sulphide inclusion below). It is suggested that the sulphur derived from coal included in the Fife ores. Metal retrieved from the site was white cast iron, but the limited excavation undertaken by GUARD on behalf of Letterewe Estate did not produce evidence for casting pits. Privy Council accounts suggest that no Letterewe guns were sold to the Crown (M Caldwell, National Museums of Scotland, pers. comm.), so it is likely that Sir George Hay's markets may have been the merchant navy, England, Ireland or abroad.
Sir George Hay, High Chancellor of Scotland
(Dixon 1886: Gairloch and Guide to Loch Maree, Gairloch & District Heritage Society, Edinburgh)
Letterewe furnace site
"Rabbit-like" inclusions of MnS in sulphur and phosphorous-rich iron from Letterewe Furnace, Western Ross.