I can't get excited about opals but I quite like opalised fossils. These shells are in the wall of a museum we visited in Coober Pedy - about four metres underground. And we've seen other fossilised marine animals and plants as well as trees and plants.
We drove around Coober Pedy to see what the real estate is like, and decided that we'd quite like to live (for a little while you understand) in a large and comfortable underground mansion dug into a north-facing hill that overlooks the plain below. It would be interesting to know if they are freehold and what they're worth. It takes a while for the visitor to actually recognise what they're seeing - the cars and mining equipment are parked on the flat apron in front of the houses which are only evidenced by a front door and a window or two or a verandah.
Of course the environment is cactus, both underground and above ground. Mullock heaps everywhere.
Water is a precious commodity here. It's piped in from the artesian basin, desalinated and filtered through a reverse osmosis filtration system so it tastes very sweet. We needed to top up our water containers so we went to the only water-filling station in town and paid 20c for 30 litres. Imagine what it was like here in the 'olden days' when water was even more precious.
We also drove out of town on the road to Oodnadatta to see the dog fence. After watching a farm dog at 'Melrose Station' near Winton walk across a cattle grid, slowly and carefully placing all four feet on the grids, I'm not convinced that this one would stop a determined dingo from crossing to the south side.