About: http://webisa.webdatacommons.org/63272174

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	A variety of marketable materials are mined in subsurface operations, including gypsum, salt, clay, iron ore, gold, lead, zinc, limestone, coal, and other minerals and metals.
http://www.w3.org/ns/prov#wasQuotedFrom	dot.gov