Assertion: opal's value | /r/HasProperty | overshadowed by the discovery of copper
Facets:
value: at kapunda
type: LOCATION
Source sentences:
text: The value of these mines was soon overshadowed by the discovery of copper at Kapunda (1842), Burra (1845) and in the Copper Triangle (Moonta, Kadina and Wallaroo) area at the top of Yorke Peninsula (1861).