Not sure if this is what you are after... but you may find some useful references in this paper:

Darvill, T. 2002. White on blonde: quartz pebbles and the use of quartz at Neolithic monuments in the Isle of Man and beyond. In A. Jones and G. Macgregor (eds), Colouring the past: the significance of colour in archaeological research, 73-91. Oxford: Berg.

I think Cooney also mentions modern usage in Ireland in:

Cooney, G. 2000a. Landscapes of Neolithic Ireland. New York: Routledge.

Best, Buck.

p.s. your photos continue to amaze me – keep up the excellent work!