an especially rich vein of precious ore
"The prospector's eyes widened when his pickaxe struck a massive bonanza of pure gold deep within the mountain."
A rich mine or vein of silver or gold.
"The prospector celebrated when his shovel struck a bonanza of pure gold in the rocky hillside."
A city in Klamath County, Oregon, United States.
"After visiting Bonanza to see its historic buildings, we drove back toward Eugene for dinner."