I have no idea but a big part of this hobby is the enjoyment found travelling to out of the way places to find the stones. I'd be starting by walking or snorkling fresh water streams. If you get the water worn ones then you have an idea what they'll look like pollished.
Contact the York Peninsula Gem and Mineral Club - They are based at Moonta and have well equipped clubrooms. The members are very welcoming and willing to share their knowledge.
Yorke Peninsula Gem and Mineral Club PO Box 534, Kadina SA 5554 Secretary: Janet Petherick, Email, [email protected]