11. Some of the best ones are unusual colours. 12. Or are pure white, like quartz. 13. Pebbles that have veins of a different colour rank very highly. 14. So do rocks that have been smashed apart ...

A recent study also suggested that the site was part of an ancient trade route that carried goods from across the continent and the excavation revealed a strip of quartz pebbles. Knewz.com ...

Banded vegetation, with its intriguing ‘tiger stripe’ patterns of bare and vegetated ground, is a striking feature of arid ...