bronze age Chalcolithic use of jet and jet-like materials

In Scotland there is no jet and jet-like object that can be attributed with certainty to the Chalcolithic period (i.e. 25th - early 22nd century BC), even though evidence from elsewhere in Britain (at Chilbolton, Hampshire and Devil's Dyke, Sussex) suggests that tiny disc beads of these materials may have been in use - as part of composite necklaces, along with tubular sheet metal beads - during this period. These beads are associated with Beaker pottery in graves and represent a Continental fashion: their shape echoes that of copper spiral beads in central Europe.