The Venetians and the Franks called the island “Arzantiera”, that is Silvery, for the grey-white rocks they saw as they approached the island. Some travelers believed that the name was due to ancient silver mines, but they have not been discovered so far.
In contrast with most of the islands of Cyclades which belong to the Attica-Cyclades Mass and consist mainly of transformed rocks, Kimolos is for the largest part the product of intense volcano activity as it lies on the outer zone of the volcanic arc of the Aegean and the traces of volcanic activity are visible all over the island: hot springs and unusual geological formations that create sites of extraordinary beauty. 
The most usual rocks of the island are volcanic ones: of the riolithic type, although granite is not rare.
The pre-volcanic substratum appears in very few places. A large area of the island is covered with tuffs and tuffites.
Tuffs are easy to process, light volcanic mineral which is used as building material, usually cut in a shape of parallelepiped.
These pieces are called “poria” by the people of the island. Their excavation and commerce was in the old days a significant income for the people, since they transferred them with trawlers to long distances both in Greece and abroad. The impressive remains of the excavation on the road uniting Chorio with Klima, near Agios Nikolas and on the eastern side of the bay of Agios Minas provide a picture as to the size of this activity.
The erosion of the volcanic minerals by the water from the hot springs, the rain and the sea enriched the island with industrial minerals, mainly bentonite, but also pozzolana (white cement), perlite, kaoline (porcelain), ferromanganese (older excavation), barite, zeolite and some sulphur.
Zeolite is a material that relatively recently was used in various important applications, like the separation of gases, environment-friendly detergents, cleaning the sea and the water in general from heavy metals and toxic substances etc.
Relative to the above is a unique type of argil, the “land of Kimolos”, which took its name by the island, with detergent and pharmaceutical qualities, known from the prehistoric years. The Cretans of Minoan era imported large quantities for whitening wool filaments. Lumps of this material were found at the Sanctuary of Artemis in Vravrona and possibly were a dedication. The athletes used it to clean their bodies from oil. The Romans called “chalk” other types of argil that had similar qualities and different origin. Of course the “Kimolos chalk” has no resemblance with the well known chalk we use in classrooms. The latter, whose correct name is “kritis”, took its name from the former because it is somewhat alike in colour and texture.
Semi-precious minerals, mainly quartz variations, like amethyst, agate, chalcedony, jasper, opal are usual on the island. Many colored crystal and microcrystal variations can be found at masses of minerals (cavities of rock with multicolored zones and large beautiful crystals).
If you belong to those who love to collect pebbles you will find a lot with nice variations of the above minerals.
On the road to Aliki, just before you turn towards the beach you can admire small, shining “artifacts” of a variety of barite called “Rose of the Desert” because it resembles a fully bloomed rose. At the same beach you can find many pieces of holy stone.
Text: George A. Ventouris, Despoina Athanasiadou-Ventouri
