The gold and silver mines of Sifnos: In the ancient times, Sifnos was famous for its mines of gold and silver. There were many mines on the island but the richest were the mines of Agios Sostis. These mines had given prosperity to the island and also had caused many attacks, such as the attack of the Samians, in order to conquer the island. Although the soil of Sifnos also has schist, marble, copper, and iron, the goldmines and silver mines were the richest in stock.
The mining activity of Sifnos is even mentioned in the writings of Herodotus and Pausanias. Also, to thank the gods for this source of prosperity, the locals used to send to the Oracle of Delphi, many valuable offerings every year. These offerings were kept in the Treasury of the Siphnians, which can be seen even today in the site of Delphi. The myth says that one time, the Siphnians omitted to send their offerings and as a punishment god Apollo flooded the mines. In fact, these mines are flooded till today as they are found in the same level to the sea.