This scarf shows off a laceweight Noro yarn: Sekku. It's a very thin fiber – a true lace yarn - spun with cotton, wool, nylon and silk. It's very soft and makes up into lovely lace. Karen's scarf took all of 1 skein with a very tiny crochet hook.
It would also be very lovely carried along with a laceweight mohair-type yarn.
Karen will have the pattern written up soon!