Bunbury Agate. On beaches in the area. A white to clear chalcedony, sometimes with gas and liquid inclusion. Polishes up nicely, like moonstone.
Could see industrial wharfs from the beach we visited, but don't know its name.
Believe the deposit to be offshore of the beach, and either insitu, dumped or dredged. Sorry no further details.
Was there many years ago so maybe worked out now.
A West Australian Lapidary club would be an ideal starting place. there is one in Rockingham and another in Perth.
Welcome to ALF. Hope you and dad enjoy the hobby.
Regards,
Ghost.