Geschichte: On a breezy morning, we were hiking across the southernmost tip of Kos on day one of an excursion to explore the Greek island's rich volcanic history. The break we took at a quarry on Mount Zini was the best stop of the entire week-long trip! Not only were the views of Kefalos Bay breathtaking, but the rocks lying around contained little black pearl-like structures that I had never seen before.
Geologie: This rock was once volcanic glass which formed from a cooling lava flow. After the flow's formation, water intruded from the surface along cracks and 'decomposed' the glass forming the light-coloured material. Some of the volcanic glass survived the water's 'attack' however. These left-overs are visible as roundish, pea-sized black spheres that resemble pearls - hence the stone's name perlite.