The great Georgian tradition (Georgia in the Caucasus) of making wines in terracotta “Qvevri” is dating back to about 6,000 BCE. Qvevri (Georgian: ქვევრი) is a large (100-5000 liters) earthenware vessel, resembling an egg in shape.
The qvevri wine making is carried in qvevri completely buried in the ground, so that even the outlet neck of it remains below ground level. The most unusual and archaic, the most traditional Georgian qvevri wines is of course white Kakhetian qvevri wine (also known as orange or amber wine), macerated for several months with the skins, seeds and stems of the grapes in the buried qvevri.
The best qvevris were made from special clay with high lime content - marlstone. That's why such qveris after being fired gained the highest strength. Nowadays, marlstone is used for cement - concrete production.