Ironstone calcining kilns at the top of Rosedale Chimney Bank built around 1860 to serve Hollins mines, the source of the mysterious magnetic ironstone which contained 71% iron content, so rich in iron it would hold a simple magnet. The kilns were originally much higher (see photo below, c. 1930) but since the mines closed in 1911 a combination of weather and stone salvage has reduced their height considerably.
![](http://www.northyorkmoors.org.uk/__data/assets/image/0012/1205013/Bank-Top-Kilns,-date-and-source-unknown.jpg)