About: http://webisa.webdatacommons.org/229019715

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	Carbon and iron are products of nature, but steel is a natural product (mixture of carbon and iron) and not a product of nature.
http://www.w3.org/ns/prov#wasQuotedFrom	patentdocs.org