It's a sort of crystal that is formed under the sand - something to do with certain minerals having a reaction the the evaporation of water. They are really hard to photograph, but in real life they are really sparkly and beautiful!!

WHERE TO DIG??? You actually need to get the GPS Co-Ordinates from someone who has already found some, then you just drive into the desert to the same spot, and start digging They are usually about a meter under the surface.

At one point we were up to our knees in water in the holes we had dug, and within 15 minutes the water was only ankle-deep - then we realised that it was the water table dropping as the tide went out at the coast, about 100 kms away!! It was amazing!!Here is a nice pic of some on the internet!