This is the history of two mining districts and one railway line. Two well-matched mining companies which worked on opposite sides of the same mountain and used the same train. From the Troi-Aztiria mines (Mutiloa mining district) the Compañía Minera de Mutiloa extracted hematites from placers (residual deposits) which were washed at Monastegizar, although a small vein of hematites with quite a lot of lime (iron carbonates) was also exploited and enriched by calcination in a kiln near Ormaiztegui station.

In order to transport the ore to the processing plants, the Compañía Minera de Mutiloa decided to use mountain trains pulled by steam locomotives. The Mutiloa-Ormaiztegi railway started up in 1901 with two locomotives, with a total capacity of around 300 metric tons a day. The ore travelled down an inclined plane from the mining district to the Barnaola country house. There it was loaded onto the wagons and the Mutiloa railway carried it to Ormaiztegi station, where it was transferred onto the Ferrocarril del Norte trains.

The Cerain Iron Ore Company Limited extracted iron carbonates from the Aizpea mining district in Zerain, on the other side of the mountain which rises above the Barnaola country house. This British company built a mountain railway just 1.5 km long. A train pulled by a steam locomotive collected the ore extracted from the various mines and carried it in wagons to an inclined plane, where it travelled down to the calcining kilns at Aizpea. After the calcining process, an aerial tramway some 3 km long carried the ore to the Barnaola country house, where it was also loaded onto Mutiloa’s trains.

The two locomotives of the Mutiloa railway company, both called Mutiloa, ran for the last time in 1927. Here ends the history of the railway but not of the mines. The Troya mine at Mutiloa continued its operations until the 1980s. At Zerain, the mining operation was taken over by the German company, Aralar, in 1932 and the company Patricio Etxeberria of Legazpi prolonged its life from 1941 until its definitive closure in 1951.