Milos lies on the South Aegean volcanic arc. The volcanos of the island may be dormant today, however there are several indications on the island that its surface communicates with the interior of the Earth. These are indications that can be met in all volcanic arcs with signs of recent or older volcanism.
In Milos there are fumaroles (gas sources), mainly on the eastern and southeastern side of the island. These are areas that let, due to the tectonic structure, gases that come from the Earth’s interior escape (vapors, carbon dioxide, hydrogen sulfide, etc). Characteristic of these areas is the yellow colour and the odour of sulfur, while the soil temperature is very high. Fumaroles also exist in underground areas where the yellow colour of sulfur is also characteristic. Gases, in the form of bubbles, reach the surface of the water. Such areas are Aghia Kyriaki, Paleochori, Kanava, Rivari.
Apart from the fumaroles there are also hot springs. They can be found in various places around the island, close to the sea level, some of which are thermal springs (spas), without however being properly used. Such springs can be found in Adamas, Alykes, Kanava, Paleochori, Mandakia, Provatas, Tria Pigadia, etc. A typical feature of these areas is that there are very high soil temperatures. All these surface high temperature conditions have acted over time in such a way that the soil has been altered, producing thus various exploitable minerals and rocks.
Thus, the mining activity began in pre-historic times and continues until today, with the exploitation of the same minerals and many times of the same mines. There are approximately 200 mines all around Milos. Today, 90% of the production is in the hands of the seven major corporations that are active in the sector, and of an equal number of smaller corporations. They mostly mine kaolinite, bentonite, perlite, silicates and pozzolana. There is also a number of individuals, who conduct seasonal or more systematic mining of products that they usually sell to the major companies.
The total area of the owned or leased locations that these companies exploit does not exceed 9% of the total surface of the island. The deposits of these areas, with the important production rates of these companies are adequate for the next 50 years, as can be demonstrated by the data of the Special Planning Study which took place in 1993.
Regarding the already mined materials, it is possible that the corporations will not be interested to expand their activities. This does not mean,of course, that the research work in order to locate new deposits of the aforementioned minerals, or to find new ones, will cease. This is why a contract has been signed in 1992 between one of the corporations – S&B Industrial Minerals S.A. – and the Greek State for the search of gold-bearing deposits, in the island group of Milos, with the interest being targeted in the meridian slopes of the hill of Profitis Elias in the western part of the island, an area that has been declared as Environmental Protection Zone in the Planning Study.
During the 1981-1995 period, in an area of 122,000,000 square meters which has been delimited for mineral prospecting and mining of ore, mining corporations, research centers such as IGME (Institute of Geological and Mineralogical Research), and universities, conducted their mineral research and discovered new minerals, such as zeolite, amorphous silica, potassium feldspar and gold (Milos Planning Study, 1981). In 1995, the area for the conduction of mineral research was limited to 18,175,000 square meters (Special Planning Study, 1993).
Regarding the mining ports and loading installations, there are such facilities in Xylokeratia, Voudia, Kanava and Ambourdehtaki.
TYPES OF MINERALS
The following minerals are the main minerals of Milos:
Perlite, Baryte, Kaolin, Bentonite, Pozzolana
There are also other minerals, such as silver, sulfur, obsidian, millstone, manganese, alunite, gypsum, and siamite, and, as it has been already mentioned, in the last decade have been discovered zeolite, amorphous silica, potassium feldspar and gold.
Perlite is located in the southern part of the island near Alykes and in the northern part near cape Kerdari, where two perlite mines exist, in Trahilas. Another perlite mine can be found in the southern part, in Provatas.
Baryte can be found mainly in the northeastern part of the island, near the foot of the hill Korakia, and, in smaller quantities, in the northwestern part of the island, in Kokkino Vouno. Two baryte mines exist in Pikridou, in the northeastern part of Milos.
Kaolin does not present a spatial concentration as it is spread all over the southeastern part, in Hondro Vouno, and in the western part of the island, in Kokkino Vouno to the northwest, and in Mikro Vouno to the southwest. There are three kaolin mines in Ralaki Halakas, in the eastern part of Milos, two mines in Paleochori, in the southwestern part, and three mines in Kastriani, near Tsiknias, in the western part of the island.
Bentonite is concentrated in the northeastern part of Milos near the hill Korakia and the hill Gerakopetra. The bentonite mines are concentrated in the eastern part of Milos; there is a mine in Trogalas, in Akoureftou, in Garyfalakena, in Pikridou and in Aggeria, and there are two mines both in Komia and in Voudia.
Pozzolana can be found in the southern part of the island on the Mavrovouni hill, while at the foot of the hill, in Xylokeratia, there are also two pozzolana mines.
There is also a siamite mine in the southern part of the island, in Lagoudina, while the sulfur mines of Milos that are located in the southern part of the island, close to Thymia, are inactive.