Gyali

Gyali island is a volcanic island situated between the islands of Kos and Nisyros. It is renowned for its pumice and if you ever get to pass by the island you will certainly not fail to notice the extensive pumice strip mining that is taking place, leaving Gyali island to a large extent quite barren of vegetation. The island is very long, around 6 kilometers while its width ranges from 500 meters to 4 kilometers.

For more information you can check this link: https://en.m.wikipedia.org/wiki/Gyali