Assertion: oak's bark | /r/HasProperty | rich
Facets:
value: in tannic acid
type: OTHER
Source sentences:
text: Its inner bark, like that of most other oaks, is rich in tannic acid, which is used for tanning purposes.
text: Bark and leaves of sumac are rich source of tannins that are used for the tanning of leather.
text: Its inner bark, like that of most other oaks, is rich in tannic acid, which is used for tanning purposes.