By Mohamed El-Hebeishy Out of 18 sand seas that exist on this planet, four are in Africa. The largest is the rightly-named Great Sand Sea. Occupying a massive part of the Western Desert of Egypt, it misleads people into thinking there's nothing to see but endless sand dunes. Indeed there is sand, loads of it, but there also lies Silica glass. Mohamed El Hebeishy, among many, would like to know where it came from In this wide world of ours, only a part of the Great Sand Sea plays host to a unique natural formation, Silica glass. Silica glass comes in varying degrees of clarity ranging from cloudy to transparently clear. Its colour ranges from steak grey to pale green while its weight may vary from a few grammes to a 27kg-chunk, the biggest whole piece ever found. Scientifically speaking, in order to form Silica glass, it needs to be heated at 1600� C for 47 days or 2000� C for only two minutes. Theories attempting to unravel the formation mystery of Silica glass may attempt to suggest volcanic activity or a non- terrestrial origin. The most acceptable hypothesis is that its formation was due to a meteorite impact. To add a touch of charm to the enigma, Vincenzo de Michele of the Centro Studi Luigi Negro examined Tutankhamen's pectoral jewellery in October 1998 and was literally floored by what he found. The well-polished giant lime green scarab adorning the young Pharaoh was not a Chalcedon, a form of crystalline quartz, as had been previously thought. It was actually Silica glass. Did the Pharaohs discover the precious gem long before envoys of Haj Hussein of the Kufra Oasis reported it to the world? Or had they already resolved its origin mystery and buried the secret in their sealed tombs? Questions lurk as we try to crack the ancient code encrypting Silica glass. Unfortunately, this unique natural heritage, like other representatives of our human legacy, has fallen victim to our own greed. Irresponsible tourists have become fanatic about the riddle, seizing many pieces. The big chunks are long gone and the small ones look likely to follow suit.