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The friction caused by the turning ground the leaves into a fine powder that built up around the edge of the lower-stone. The quern was held on the user's lap, the eye was filled with dried tobacco leaves and then the upper-stone was turned using the handle. Snuff-querns consisted of an upper and lower stone, fixed together by a central iron pivot. In the Shetlands tobacco wasn't smoked at first, but ground up into snuff, and inhaled up the nose. They were thus widely used in gold mining in antiquity. The aim was to liberate fine ore particles which could then be separated by washing for example, prior to smelting. Querns were widely used in grinding metals ores after mining extraction. The authors concluded that this was probably due to the use of these querns in the preparation of medicines, cosmetics, dyes or even in the manufacture of alloys. Moreover, one study analysing quern-stones noted that a number of querns had traces of arsenic and bismuth, unlike their source rocks, and had levels of antimony which were ten times higher than those of the rocks. Other materialsĪs well as grain, ethnographic evidence and Mesopotamian texts shows that a wide range of foodstuffs and inorganic materials were processed using stone querns or mortars, including nuts, seeds, fruit, vegetables, herbs, spices, meat, bark, pigments, temper and clay. In early Maya civilizations the process of nixtamalization was distinctive in that hard, ripe kernels of maize (corn) were boiled in water and lime, thus producing nixtamal which was then made into unleavened dough for flat cakes by grinding with a handstone on a quern ( metate). However, in many non-Westernised, non-mechanised cultures they are still manufactured and used regularly and have only been replaced in many parts of the world in the last century or so. They were generally replaced by millstones once mechanised forms of milling appeared, particularly the water mill and the windmill, although animals were also used to operate the millstones. Quern-stones have been used throughout the world to grind materials, the most important of which was usually grain to make flour for bread-making. Revolving beehive quern-stones and a saddlestone on display at Cliffe Castle Museum, Keighley.