About: http://webisa.webdatacommons.org/187985009

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	For this purpose, alkali metal oxides such as sodium oxide and potassium oxide, and alkaline earth metal oxides such as barium oxide, strontium oxide or magnesium oxide, can be added to the SiO2.
http://www.w3.org/ns/prov#wasQuotedFrom	google.com