The two men are standing in the middle of the sun-bleached South Australian outback, hunting for opals, the rare gemstones that can sparkle with a rainbow of different colours. They sift through ...

All opal fossils are rare - monotreme ones even more so - but these specimens are "a revelation", says Ms Smith. They take the total number of monotreme species known to have once lived at ...

The London Gem & Mineral Show returns to Sandown Park Racecourse, Esher, offering a rare opportunity to explore the world beneath our feet.