What happens when a geologist goes to Rome!
This is the Pantheon. A Roman temple turned basilica, it is the largest unsupported concrete dome in the world! In true geologist style, I got distracted by the columns outside so got a really close look (I didn't have my magnifying lens on me).
They are made of granite, a rock which formed underground as molten rock slowly cooled and solidified.
This is why the mineral crystals are large and distinctive, with the pink crystals (orthoclase feldspar) much larger than the dark grey (quartz), white (plagioclase feldspar), black (biotite) and green-grey (hornblende)

















