Hi OlivineOlivia888, welcome to the forum. Not sure if Mount Shadwell is still open, it's near Mortlake. If you do a search here on either Mount Shadwell or olivine you get heaps of info. Also Mooralla, near the Grampians has some nice smokey quartz, but you have to work hard for it. That's about the extent of my knowledge on the area, maybe someone from SA could help with closer to Mount Gambier.