Cyclonite, Hexogen, RDX - its all the same stuff. See:
http://www.saudiform.com/hexamine.html#PHYSICAL
Funny that the first website in English you get when you Google Hexogen is a Saudi one.
But anyway it's a white crystalline granular compound visually indistinguishable from sugar. The only way you can distinguish it is with an infra-red spectrometer or possibly with one of the new scanners at:
http://www.manchesteronline.co.uk/ne...a_breeze_.html
But until such scanners have been installed at all bagagge scanning points watch out for people carrying bags of groceries with them on to your aircraft.