'Krystallen' for flute and piano was written in 1973 for the flautist Susan Milan who gave the first performance on BBC Radio 3 with Clifford Benson in January 1975.The music is in three sections the last of which is avaried repeat with palindromic elements of the opening. These outer sections are texturally three-part inventions consisting of gently interweaving equal-voiced polyphony while in the central passage individual figures areisolated and exchanged by both instruments.