Iron ore
In cast iron sulfur promotes the formation of white iron. As little as 0.5% can counteract the effects of slow cooling and a high silicon content . White cast iron is more brittle, but also harder. It is generally avoided, because it is difficult to work, except in China where high sulfur cast iron, some as high as 0.57%, made with coal and coke, was used to make bells and chimes . According to , good foundry iron should have less than 0.15% sulfur. In the rest of the world a high sulfur cast iron can be used for making castings, but will make poor wrought iron.
Wealden iron industry
The Lamberhurst Foundry is believed to have been the maker in 1710–14 of some of the earliest cast-iron railings produced in England, which they made for St Paul's Cathedral, despite the objections of Christopher Wren, who did not want a fence around the Cathedral at all, and said that if there had to be one it should be of wrought rather than cast iron. The railings surrounded the cathedral, including seven gates. It weighed two hundred tons and cost six pence a pound. The total cost was £11,202. No further railings are known to have been cast in the Weald. Other early uses of cast iron railings were at Cambridge Senate House and at St Martin-in-the-Fields, London.