About: http://webisa.webdatacommons.org/337001103

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	Hardness is a factor so it does not scratch easily or get colored by chalk.
http://www.w3.org/ns/prov#wasQuotedFrom	billiardsdigest.com