 Laskill, an outstation of Rievaulx Abbey and the only medieval blast furnace so far identified in Great Britain, was one of the most efficient blast furnaces of its time.Slag from contemporary furnaces contained a substantial concentration of iron, whereas the slag of Laskill was low in iron content, and is believed to have produced cast iron with efficiency similar to a modern blast furnace.The monks may have been on the verge of building dedicated furnaces for the production of cast iron, but the furnace did not survive Henry's Dissolution in the late 1530s, and the type of blast furnace pioneered there did not spread outside Rievaulx.