While driving through outback Queensland I passed what I thought were smallish lumps of coal strewn along the roadside. Only when I stopped to stretch my legs did I discover that they were fossilised sections of wood and surprisingly heavy. I kept one, and still use it as a paperweight.
On the same trip I tried gold panning in New South Wales and opal noodling in Coober Pedy and found absolutely nowt, which gives me agreat excuse for a return trip.:-)