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.
Ferrous metallurgy
The earliest cast iron artifacts, dating to 5th century BC, were discovered by archaeologists in what is now modern Luhe County, Jiangsu in China. Cast iron was used in ancient China for warfare, agriculture and architecture. Around 500 BC, metalworkers in the southern state of Wu achieved a temperature of 1130 °C. At this temperature, iron combines with 4.3% carbon and melts. The liquid iron can be cast into molds, a method far less laborious than individually forging each piece of iron from a bloom.