By the end of the 1950's, numerous machines and devices had been taken out of operation by the mine. For three decades, these precious specimens of technical mine heritage were on display to visitors in the courtyard of Gewerkenegg Castle. Exhibited in open air, they were unfortunately exposed to varying weather conditions and, at the beginning of renovation works on the castle and its courtyard in 1988, were found to be in very poor condition. Museum and other experts finally decided that the mine machines needed to be thoroughly and permanently protected in an authentic, mining environment. Today, 26 specimens dating primarily from the late 19th and early 20th centuries are exhibited in three indoor exhibition rooms alongside the entrance building to Francis' Shaft (named after Franz II, Roman-German Emperor from 1792 to 1806, after which he acceded to the Austrian throne as Franz I).

The collection comprises three turbopumps, a diesel engine and three compressors from the early 20th century, two winches, two steam piston machines from the late 19th century,  three pumps for steam boilers, a steam-powered transport machine, a steam boiler and a Francis water turbine from the late 19th century, a shaping machine, planing machine, radial drilling machine, lathe, thread – cutting machine, a power hammer and band saw from the late 19th century, a drilling set for deep drilling, and a pit telephone. Two machines are equipped for operation on compressed air.

Four locomotives and five trams for transporting ore are exhibited in the former loading station of the cableway at Joseph's Shaft.

Kley's pump is the largest preserved machine of the Idrija Mercury Mine, the largest preserved steam-powered machine in Slovenia and probably also in Europe. The mine decided to purchase the pump after a sudden inrush of pit water in 1885. The inflow of water was greater than the capacity of all available pumps. The steam pump was manufactured in 1893 by the famous E. Skoda Pilsen factory (Plzeň – industrial town in the western part of the Czech Republic). Individual components of the pump were transported by rail to Logatec, and then to Idrija by horse-drawn wagons. The pump began to operate in 1895, and according to currently available data it was put into operation for the last time in 1948, and disassembled seven years later. Owing to the enormous size and weight of its component parts, the machine aroused considerable admiration.