> some beautiful shades of red, ranging from pale rose pinks to an almost> purple colour. I know the reds & yellows come from iron, but I don't know> about the purple.
Manganese?
See e.g. http://web.uct.ac.za/depts/geolsci/dlr/kirstenbosch/mang1.htm
Nice fresh-hewn sandstone btw.
DLM
