Assertion: pennsylvania anthracite | /r/HasProperty | mined
Facets:
value: heavily
type: DEGREE
value: during early 1900s
type: TEMPORAL
value: during the late 1800s
type: TEMPORAL
Source sentences:
text: Pennsylvania anthracite was mined heavily during the late 1800s and early 1900s, and remaining supplies became harder to access because of their deep location.