Chapter 6 Scottish mineral Geological Conservation Review sites — Late-stage hydrothermal minerals

Abstract This fifth paper on Scottish mineral Geological Conservation Review (GCR) sites describes five sites of highest conservation value that reflect a wide range of mineral occurrences and formative systems. Host rocks are predominantly basalts of different ages and varying compositions, although in one site the host rocks are mostly basalts and basaltic andesites. The geology and mineralogy of each site differs considerably. Many zeolites have been identified from Skye, Mull and inland localities, their formation resulted from percolating aqueous surface waters or magmatic fluids in amygdales or veins. At some localities geodes and amygdales have been filled with agates some of which are of exquisite quality. Studies of agates reveal that their origin is complex.