PropertyValue
http://www.w3.org/1999/02/22-rdf-syntax-ns#type
http://www.w3.org/ns/prov#value
  • Hydraulic fracturing, or ???fracking,??? is the process of injecting water and proppant ??? a material such as sand or other particles that prevent the cracks from slamming shut when the injection is stopped ??? into a well under high pressure to fracture the rock layer underground and release any natural gas or oil that may be trapped inside.
http://www.w3.org/ns/prov#wasQuotedFrom
  • wnd.com