About: http://webisa.webdatacommons.org/150064729

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	Alternatively, natural materials such as quartz, tourmaline, Rochelle salt, etc. may be used.
http://www.w3.org/ns/prov#wasQuotedFrom	google.fr