A microgranite formed as part of an igneous intrusion which builds the base of the Ailsa Craig island.
HerkunftGranite from Ailsa Craig island, a small rocky island in the Firth of Clyde SW Scotland
- LILE (Rb, Sr, K, Ba): 3.00-37000 µg/g.
- HFSE (Zr, Hf, Th, U, Nb, Ta) 5.00-800 µg/g.
- Transition metals (Sc, V, Cr, Co, Ni, Cu, Zn, Mo) 0.11-224 µg/g.
Felsic rocks are characterised by a high silica content of > 69 m/m% and high concentrations of alkali metals such as sodium and potassium. Their principal mineralogy is comprised of quartz, sodium- and or potassium-rich feldspar varieties, but may also contain micas i.e. muscovite. On average the continental crust can be described as being felsic. Mafic minerals are virtually absent.