Nope, the term "Yowah nuts" is not a self-description - nor an indictment of the local population! Although ...
Yowah is a small opal field known for it's unique opal formations where the opal deposits are encased in ironstone nuts. There is a free fossicking area where hopefuls can hunt for treasure, either on the surface or by digging.
Obviously, she won't fall for that again!
Although Yowah nuts are unique, it seemed many of the best stones we admired (at the markets, with various sellers and during the opal festival) actually came from Koroit - a much smaller/more remote field further north-west.
We bought a bucket of rubble to sort through and this nut was among those. Nick chipped at it several times with a pick to reveal the "colour".