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.
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An American architectural innovation, cast iron was cheaper to use for facades than materials such as stone or brick. Molds of ornamentation, prefabricated in foundries, were used interchangeably for many buildings, and a broken piece could be easily recast. The buildings could be erected quickly; some were built in four months. Despite the brief construction period, the quality of the cast-iron designs was not sacrificed. Bronze had previously been the metal most frequently used for architectural detail. Architects found that the relatively inexpensive cast iron could provide intricately designed patterns. Classical French and Italian architectural designs were often used as models for these facades. Because stone was the material associated with architectural masterpieces, cast iron, painted in neutral tints such as beige, was used to simulate stone.