Ancient quartz quarries from which the mineral destined to glass production was extracted. It was then used at glassworks in the giudicarie valleys during the 19th century.
The Borzago quarries supplied the quartz ore needed for the glass industry. This activity was born and developed in the 1800s in the area of the Giudicarie valleys. The mineral was carried on the back of a mule or on sledges to the mill. Here it was reduced to dust in the imposing granite millstones. Thus provided the raw material for the realization of the glass composite.