So far, we have demonstrated machines that were used in the mine. The crushing mill, which is a basic machine for processing ore, was part of a foundry. It is also one of the first machines driven by the power of falling water. Our mill has an overshot waterwheel. It is the most efficient mechanism for waterwheels of all. Only the water turbine was more efficient than the waterwheel, but it was only invented more that 100 years later.
The crushing mill consists of two integral elements: crushing machine and gold launders.
The name "crushing mill" derives from the crushers - wooden beams covered with steel for crushing rocks. They are like huge hammers driven by the waterwheel. There are no written sources documenting when the first crushing mill was invented. Its prototype must have been a stone mounted on a wooden pole in the hands of the primitive man. However, the crushing mill would not be effective if driven by a vertical treadmill, regardless of its size. Only the force of falling water made it strong and efficient enough for crushing hard rocks.
Crushing mills, just like the vertical treadmills, were invariable elements of medieval foundries. Similar devices were used for grinding oak bark, which was required for tanning leather. Crushing mills were also necessary machines in brickyards and ceramic pottery yards where they ground minerals that reinforced clay. Not far from Złoty Stok, in the village Mąkolno, they were also applied in a former large gunpowder factory. According to historical sources, there were 8 crushing mills along the river there, stretching for 2 kilometres.
However, before the mine output was transported to the crushing mill, it was first manually separated from spoil in the foundry. In principle, this work should have been done in the mine by the miners if they were honest professionals, but as a rule, they did not do that, because they wanted to extract as much rock as possible. This separation work had to be done by the miners' wives or even children. There is a shaft in Złoty Stok called the Masters Shaft after the diligent and honest miners who supplied the foundry with pure ore only. After separating the ore from the spoil, it was transported to the crushing mill where it was crushed into very fine grit.
Gold launders were devices for obtaining pure ores of specific metals - in this case gold. There were many types of launders, depending on the production capacity of the foundry, the type of rock or the region - from simple troughs made from logs to complex multi-layer systems of troughs made from wooden boards. The principle, however, remained the same - after crushing the mine output, it had to be laundered in a trough (or launder) in order to obtain pure ore without any spoil residues. This process increased the content of gold in each ton of material by a few dozen percent. Only such purified gold ore was delivered to the foundry furnaces. After laundering, the quality of the ore was controlled by a skilled worker who panned it piece by piece in a special round plate (or pan) - just like the gold prospectors used to do. In this way, he determined the content of gold in the mine output. However, some ores contained gold in forms that were invisible, e.g. in compounds of other metals. This was the case of the local arsenopyrites (i.e. arsen ore containing approximately 20 grams of pure gold per ton) and loellingites (i.e. arsen ore containing approximately 35 grams of pure gold per ton). In such case, the quality controller had to smelt the ore in a special test furnace. Only then could he establish whether it was worthwhile to continue exploiting the deposits.
The mine output was laundered manually - the workers washed it in running water with simple wooden tools resembling rakes. In this way, the heavy ore settled on the bottom of the troughs (launders) while the lighter spoil was washed away by the current. The ore obtained in this process was first dried and then delivered directly to the furnaces where, after many smelting stages, pure gold was obtained.
Golden fleece is animal hide with hair, e.g. the hide of a buffalo or a ram, that has been used for thousands of years for separating microscopic flakes of gold from sand, earth and stones.
Gold prospectors put the fleece on the bottom of a wooden trough in which they rinsed a gold-bearing material. The fleece stopped the heavier gold particles while the lighter sand was washed away by the water current. Next, the fleece was washed in a wooden tub where the gold particles and heavier sediments were separated manually by panning. Alternatively, the fleece was dried in the sun, and the golden dust was shaken off before the fleece was submerged in water again. It is the oldest method of obtaining gold. It is still successfully applied today, e.g. in Brazil. However, thickly woven carpets or thick mats from artificial grass are used instead of the golden fleece.