Iron ores found in Switzerland
Switzerland is divided into three parts regarding the geological basement. The Jura Ridge, builded by folded mesozoic limestones, lay in the north. Iron ores are present in several different sedimentary beds. The most important are oolitic layers of the Dogger. But this ore is relatively poor and has been mined only during recent periods. The siderolitic iron ore (Eocene) was more attractive for the ancient miners because it is easy to recover rich pisolitic concretions.
On the central Plateau, the sediments are very recent and do not contain any iron ore. But this is the more attractive part of the country for agriculture and most of the population settled in this area.
The Alps are high mountains with a very complicated geology. There are several small ore deposits in this area but they are more difficult to mine, but most of them have been exploited during the recent past at least.