Australian export (5)
I believe the answer is:
opals
'australian export' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for opals that I've seen before include "Milky sparkling gemstones" , "jewels" , "Translucent gemstones" , "Milky gemstones with delicate colours" , "Iridescent gems" .)