Assertion: lead pencil's lead | /r/HasProperty | obtained by oxidative roasting of pbs
Facets:
value: to crude pb
type: TRANSITIVE-OBJECT
value: with subsequent reduction of pbo
type: OTHER
Source sentences:
text: Metallic lead is obtained by the oxidative roasting of PbS with subsequent reduction of PbO to crude Pb (lead bullion), which is then refined (purified).